JPS5947918B2 - Color television signal recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to VIR (Verical Interval Re
The present invention relates to a device for recording and configuring color television signals including VIR signals, and provides a recording and reproducing device that accurately records and reproduces VIR signals and eliminates saturation changes and phase changes in color television receivers. be.

Traditionally, color television signals have been converted to VHF or UH.
When transmitting at F, there is a problem that distortion in the transmission system causes fluctuations in the phase and amplitude of the color signal, so when transmitting, the VIR signal as shown in Figure 1 is
It was used for so-called inter-station adjustment, in which the VIR signal was inserted into every 9 scanning periods (FCC standard) and transmitted, and the phase and amplitude fluctuations were corrected based on this VIR signal at stations where broadcasting stations were interrupted. For example, this VI can be used even on color television receivers.
Color television receivers have appeared in which the saturation and phase of color signals are controlled by the R signal.

The VIR signal is configured as shown in FIG.

That is, a is a horizontal synchronizing signal, b is a burst signal whose phase is on the one (BY) axis, and c is a chroma difference signal (VIR) having the same amplitude and phase as the burst signal of b. FIG. 2 shows a burst signal and a chroma difference signal in vector form, with the burst signal being shown by B and the chroma difference signal being shown by R. VI in Figure 3
The normal positions in the first and second fields of the R signal are shown at A and B, respectively.

Now, when a color television signal including this VIR signal is recorded and reproduced using a video tape recorder (hereinafter abbreviated as VTR) with guard padless recording, this VIR signal has amplitude and phase fluctuations for the following reasons. received,
There was a problem in which the VIR correction malfunctioned in color TV receivers, in which the normal saturation and normal hue were not reproduced.

The reason why VIR signals are not faithfully reproduced in a VTR will be explained below. This problem is particularly problematic in so-called low-frequency conversion recording, in which a normal helical scan type VTR angle-modulates the luminance signal, converts the carrier color signal to the lower frequency side, and records and reproduces the signal by superimposing it on the angle-modulated wave. This problem occurs in VTRs that use a reproduction method that eliminates guard bands between recording tracks.

In other words, since the guard band is eliminated, crosstalk from adjacent tracks occurs due to tracking errors, etc., which becomes a damage prevention signal and is mixed into the reproduced signal from the main track. Therefore, in order to reduce the influence of crosstalk from adjacent tracks, the head axis angles (for example, ±6°) are recorded differently between adjacent tracks.
The crosstalk component is reduced by the azimuth loss. Therefore, the azimuth recording method is currently used for guard bandless recording. By the way, this azimuth loss is larger as the wavelength becomes shorter. That is, an FM signal obtained by angle-modulating a luminance signal (for example, FM modulation) has a large azimuth loss, but a carrier color signal converted to a low frequency (several hundred KHz) has a long wavelength. Therefore, azimuth loss is small. Therefore, in order to eliminate adjacent crosstalk, the frequency spectra of recording carrier color signals between adjacent tracks are recorded in a frequency interleaf relationship as shown in Figure 4 (the solid line is the spectrum of the main track, and the broken line is the spectrum of the adjacent track). During reproduction, a method is used in which only the main signal is separated from the conveyed color signal using a comb-shaped filter using an I horizontal scanning period (IH) delay line. This comb-shaped filter using an IH delay line uses the correlation with the signal before IH to add the main signals and eliminate crosstalk. The chroma difference signal (Fig. 1c) of the power-converted VIR signal is a signal that has only the I horizontal scanning period.
There is no signal in front of IH (recently there is VIT on 16th to 18th
(sometimes a test signal is inserted), there is no correlation, and the amplitude and phase fluctuate due to the influence of the adjacent chroma difference signal caused by the comb filter. If there is no effect, the amplitude will be reduced by 6 dB compared to normal. Moreover, if a signal such as a VIT signal (test signal) is present before IH, this signal is added,
Depending on the content of the VIT signal, the amplitude and phase vary significantly, and color television receivers (with VIR control) have a problem in that saturation and hue vary, making it impossible to obtain a normal image.

In addition, even in recording and reproducing systems that provide guard bands between recording tracks (EIAJ, Standard-I type, etc.), color signal S
In the case where a comb filter is used to improve /N and remove cross color, the saturation level is 6 when only the VIR signal is used.
When there is a VIT signal and a VIR signal that are different in dB, both the amplitude and the phase fluctuate significantly, and there is a drawback that a normal surface image cannot be seen.

In view of these points, the present invention provides a VIR signal or a VIR signal.
Regarding the recording and reproduction of color television signals including IR signals and VIT signals, during reproduction, a comb filter is used to remove adjacent crosstalk, and recording and reproduction equipment aimed at improving S/N can also perform safe recording and reproduction. This is to send a normal image signal to a color television receiver with VIR control.

The present invention will be explained below with reference to the drawings. FIG. 5 shows a block diagram of a recording system of an embodiment of the recording/reproducing apparatus according to the present invention.

In FIG. 5, a luminance signal is separated from a color television signal from a color television signal input terminal 1 by a low-pass filter 2, and an angle modulator (for example, an FM modulator) 3
On the other hand, a carrier color signal is separated from a part of the input color television signal by a bandpass filter 5, passed through a switching device 6, and then sent to a frequency converter 7.
The frequency is converted by the continuous wave from the continuous wave input terminal 15, and the carrier color signal is converted to a low frequency (
The signal is converted into a frequency of several hundred KHz), superimposed on the FM modulated wave by a mixer 9, and recorded by a video head 10.

On the other hand, the frequency of the output of the bandpass filter 5=3.
The 58 MHz carrier chrominance signal is processed by a chroma reference signal gate circuit 11, which extracts a chroma reference signal (Fig. 7 d) using the signal from the gate pulse generation circuit 12 (Fig. 7 C), and generates a 3.58 MHz oscillator. 13 to create a continuous signal that is phase-synchronized with the chroma difference signal, and the gate circuit 14 generates a continuous wave that is phase-synchronized with the chroma difference signal using the signal from the gate pulse generation circuit 12 (FIG. 7 E). Gate and take out, V at the time of transmission
The reconfigured ROM reference signal R1 is superimposed by the switch 6 over several H periods within vertical blanking that is different from the IR signal position (19th). That is, the output of the switching device 6 becomes as shown in FIG. Note that in FIG. 7, H indicates a horizontal synchronizing signal, B indicates a burst signal, and R indicates a VIR signal. That is, in the present invention, during recording, a continuous wave phase-synchronized with the chroma difference signal of the IR signal is gated, and the NH period (n=2 or more) is inserted into the vertical blanking period.
It is recorded by being superimposed on the conveyed color signal. Further, the continuous wave 15 of frequency F8+FO is, for example, a so-called AFC circuit output 4 whose phase is synchronized with the horizontal synchronization signal of frequency k.
0fN (/c) and a 3.58 MHz (Fs) oscillator to obtain F8+FO. In order to frequency interleaf the carrier color signal mentioned above, F5+FO is obtained.
The output of the FO is, for example, switched so that the phase of the carrier color signal remains normal in one track, and the phase of the carrier color signal differs by 180 degrees for each line in the other track.

This technology is disclosed in Japanese Patent Application Laid-Open No. 50-142733 (β-FOrma
t method). Further, in VHS-FOrmet, the phase of FO+F8 is switched to an advanced phase by 90 degrees for each line in one track, and to a delayed phase by 90 degrees for each line in the other track. FIG. 6 is a basic block diagram of the reproduction system of the present invention.

As mentioned above, the recorded signal is amplified by the preamplifier 16 from the video head 10 and then passed through the high-pass filter 17.
A brightness FM modulated wave is obtained, amplitude and width fluctuations are removed by a limiter 18, and angular demodulation is performed by an angle demodulator 19, resulting in a reproduced brightness signal.

On the other hand, from a part of the preamplifier 16 output to the low pass filter 2
2, obtain the reproduction low-pass conversion carrier color signal, and obtain the frequency conversion product 23
So the frequency is F. After frequency conversion is performed using the signal from the continuous wave input terminal 34 of +F5, the original carrier color signal of 3.58 Mm is obtained by the band pass filter 24, and then the comb filter 25
, improve color S/N, remove cross color,
Eliminate adjacent crosstalk. The output will be as shown in Figure 8. This signal is sent to the mixer 33 after removing the reconstructed chroma difference signal inserted at the time of recording and the chroma difference signal from the time of transmission by the switch circuit 28.
is guided by the mixer 32 during the 19th horizontal period.
The chroma difference signal is added to the reproduced luminance signal in the mixer 20 and connected to the reproduced video output terminal 21.

The comb filter 25 uses a subtracter 27 to subtract the signal output from the bandpass filter 24 and the signal delayed by the IH delayer 26, and due to line correlation, the carrier color signal component is doubled and recorded. Adjacent crosstalk is arranged to be removed when the carrier color signals are frequency interleaved between tracks.

The output of the comb filter 25 (FIG. 8) is used in the reconstructed ROM reference signal gate circuit 29 to extract a reconstructed ROM reference signal using the gate pulse shown in FIG. 8(C) from the gate pulse generation circuit 33.

(Fig. 8 2), 3.
The 58 MHz oscillator 30 is controlled to create a continuous wave that is phase-synchronized with the reconfigured Farens signal, and the gate circuit 31 generates the signal from the gate pulse generator 33 as shown in FIG. 8, which is the 19th horizontal scanning period. At the timing shown in FIG. 1c, the phase-synchronized continuous wave is taken out and added to the carrier color signal in the mixer 32 to form the original carrier color signal shown in FIG. 8 or at the beginning of FIG. Further, the switch circuit 28 removes the carrier color signal using the signal shown in FIG. Frequency F during playback.

Although not shown, the +F8 continuous wave (continuous wave input terminal 34) has a frequency of, for example, 40, which is phase synchronized with the reproduced horizontal synchronization signal.
A so-called APC circuit obtains a burst signal from the /H continuous wave and the output of FIG. It is created by the output of a so-called AFC circuit that is previously phase-locked to the horizontal synchronization signal. That is,
Low-pass conversion carrier color signal frequency F. becomes FO±Δf due to time axis fluctuation during reproduction. The continuous wave input terminal 34 has an APC,
If F8+FO±Δf from the AFC is added and a difference component is taken by a frequency converter, time axis fluctuations are removed. Also, during recording, the recording carrier color signal between tracks is frequency interleaved, so the frequency F is the same as in recording. +F
By switching the phase of the 8th continuous wave, the reproduced carrier color signal (6th
As for the main signal (output in FIG. 24), since the main signal is adjacent to the original phase and the phase of the crosstalk differs by 180° from line to line, the crosstalk can be removed by the comb filter. Now, in Figure 9, VH
The recording pattern of S format (2 hour recording) is shown.

In the 19th horizontal scanning period, the VIR signal indicates the position of the chroma difference R.

In the 10th to 15th horizontal scanning periods, reconstructed rear lens signals R1 are recorded (first cross rear lens signals (to FIG. 7)) T, , T.

,T. , T4 indicate tracks.Adjacent crosstalk removal will be explained based on FIG. 9.

If track T1 is currently being played back, the crosstalk is the signal from track T2.

FIG. 10A shows the output of the bandpass filter 24 of FIG. 6 at 3.58MHz. In the reproduced carrier color signal, the solid line indicates the main signal phase and amplitude. The broken lines are interleaved in frequency due to crosstalk, so each line has a 180° phase difference. The opening in FIG. 10 shows the phase and amplitude of the IH-delayed signal of the 26 outputs in FIG. C is the result of subtracting mouth from A and is the output of the subtractor 27 in FIG. 6, which is the output of the so-called comb filter 25. As shown in Figure 3, crosstalk remains in the 9th and 16th horizontal scanning periods of track T1, and the amplitude of the R signal in the 10th horizontal scanning period is 6 dB lower. In the first chroma difference signal extraction, the first chroma difference signal in the 13th horizontal scanning period is extracted as shown in FIG. 8C. In other words, there is no crosstalk,
A chroma difference signal with normal amplitude and phase at the time of transmission will be extracted. Similarly, when track T2 is the main signal, tracks Tl and T3 cause crosstalk, and when track T3 is the main signal, tracks T2 and T4 cause crosstalk. Considering these in the same way, in the pattern shown in FIG. The insertion period of the chroma difference signal of No. 1 is at least 6H period (for example, 10~
15th) is required, and the position from which the first chroma difference signal is extracted during playback must be the 13th position. This means that the minimum required period of the first chroma difference signal and the gate position of the first chroma difference signal during reproduction differ depending on the pattern. In short, this means extracting a position from which adjacent crosstalk has been removed. Further, there is no problem in lengthening the first reconstructed chroma difference signal insertion period. Further, in this embodiment, the insertion position is set from the 10th H, but in a helical scan type VTR, this is set to 5 to 8 H before the head switching position (the leading edge of the vertical synchronizing signal). There, skew occurs due to head indexing, tape expansion/contraction, and other factors. Therefore, the VTR's AFC
The circuit generates an error and takes 5 to IOH periods to stabilize. Since the phase of the carrier color signal is not stable during that period, in this embodiment it is set from the 10th time, but this can be done later.
Also, when there are VIT and VIR signals at No. 17 and No. 18, respectively, the VIT and VIR signals are added by the comb filter during playback, and the VIR signal fluctuates in amplitude and phase. In circuit 28, the 19th V
The IR signal (chroma reference signal) is removed and replaced with a new second reference signal, so that it is not affected by the VIT signal either.

In addition, in FIGS. 5 and 6, the 3.58 MHz oscillators 13 and 30 are connected to the chroma reference
It goes without saying that the 3.58 MHz oscillator may be controlled by comparing the phases of the 3.58 MHz oscillators and sampling and holding the error voltage.

Furthermore, since the sample and hold time extends over one field, a circuit for stabilizing the phase may be required. The gate pulse generators 12 and 33 separate the synchronization signal from the color television signal, and use the vertical synchronization signal and horizontal synchronization signal to create the gate pulses shown in FIGS. 7 and 8.

In addition to the vertical synchronization signal and the horizontal synchronization signal, a stable signal phase-synchronized with the video signal used in the VTR may be used.
Next, as the first chroma difference signal insertion position, an example of a configuration in which the gate pulse generation circuit is relatively simple is described as the first chroma difference signal insertion position.
This will be explained using Figure 1. In Figure 11, A is a color television signal, and the end is a carrier color signal, and the horizontal synchronization signal period H shown in A.
Recording and reproduction are performed by inserting the first reference lens signal over the NH period (6H in the figure). In the mouth, B is the burst signal, R is the chroma difference, and R1 is the first of the reconstructions.
This is the chroma difference signal. In this method, even if the insertion period NH(7)n is large, it does not affect the video signal in any way.

'Also, as mentioned above, the phase reproduction of the chroma signal is
Even if the amplitude change (6 dB) due to the comb filter is applied, if the first folding lens signal is transmitted under the above conditions, an image with normal saturation and phase can be viewed on a color TV receiver with VI-R control. Instead of using a comb filter, a circuit such as the one shown in FIG. 12 can be used to correct amplitude changes occurring in the color television signal transmission path.

The 3.58 MHz carrier color signal from the pad hub filter 5 shown in FIG. 5 is inputted to FIG.
The 3.58 MHz oscillator 13 is controlled to obtain a signal phase-synchronized with the chroma reference signal, which is input to the variable gain circuit 36.

On the other hand, the amplitude of the extracted chroma difference signal is detected by an amplitude detector 37, integrated by an integrator 38, and the variable gain circuit 36 is controlled to synchronize with the phase of the input chroma difference signal. The amplitude becomes the same continuous wave and the output end 3
9 is output. This output terminal is connected to FIG. 514. That is, when the input power level is high, the continuous wave is also high, and when it is low, the continuous wave is low. By adding this circuit (FIG. 12) as described above, both the phase and amplitude match the input chroma difference signal. In FIG. 12, the same numbers as in FIG. 5 indicate the same circuits. Further, the same circuit can be inserted into the same operating portion in FIG. 6 during reproduction as well. The present invention does not necessarily require signal processing on the playback side to generate a continuous signal that is phase-synchronized with the reconstructed ROM reference signal inserted in the NH period, and reinsert it at a predetermined position, such as the 19th horizontal scanning period. do not.

In other words, if a signal such as VIT is not inserted into a horizontal scanning period near the horizontal scanning period in which the chroma difference signal is present, the recording side reconstructs the chroma difference signal before and after the horizontal scanning period in which the chroma difference signal exists. It is also possible to insert the signal into a plurality of horizontal scanning periods, and on the reproduction side, convert the frequency while containing a plurality of reconstructed ROM comparison signals, and superimpose it with a luminance signal via a comb filter. As long as there is phase synchronization between the reconstructed reference lens signal and the original reference lens signal, the carrier color signal that has passed through the comb filter will retain the phase and amplitude of the original reference lens signal at the predetermined position where the reference lens signal was inserted. Contains width information. For example, if the recording pattern is as shown in FIG. 9, and a chroma difference signal is inserted in the 19th horizontal scanning period of the vertical blanking period, the reconstructed reference signals 16, 17, 18 are inserted. ,
If it is inserted into the carrier color signal in the 20th and 21st horizontal scanning periods, the output of the comb filter will be affected by the absence of line phase intervals other than the 19th horizontal scanning period and the influence of crosstalk from adjacent tracks. does not convey the original information, but in the 19th horizontal scanning period, it contains a reference lens signal with both the phase and amplitude unchanged from the original information. Since a color monitor uses only the signal at this predetermined position as a chroma reference, faithful color reproduction is possible. Furthermore, even if the VIT signal is included in close proximity to the IR signal, if it is not used after playback, the recording side removes the IT signal that affects the IR signal, and similarly reconstructs the ROM reference signal. can be inserted.

As described above, according to the present invention, a normal IR signal can be obtained even in the reproduced signal of VTYL, which processes the signal using a comb filter during reproduction.

[Brief explanation of drawings]

Figure 1 is an explanatory waveform diagram of the VIR signal, Figure 2 is an explanatory diagram of the phase and amplitude of the burst signal and VIR signal, and Figure 3 is an explanatory diagram of the IR signal.
An explanatory diagram of signal insertion positions, Figure A is a carrier color signal spectrum diagram for removing adjacent crosstalk, Figure 5 is a recording system block diagram of an embodiment of the present invention, and Figure 6 is an embodiment of the present invention. 7 is a timing diagram of the recording system in one embodiment of the present invention, FIG. 8 is a timing chart of the same reproduction system, FIG. 9 is a diagram showing the recording locus of VHS format, and FIG. The figure is a diagram explaining adjacent crosstalk removal of the first chroma reference, Figure 11 is a diagram showing another first chroma reference insertion position of the present invention, and Figure 12 is a diagram for amplitude synchronization with the IR signal. FIG. 1...Input terminal, 2, 8, 22...L
PE, 3... Angle modulator, 4, 17...
・HPFl5,24...BPFl6...
・Switcher, 7, 23... Frequency converter, 9, 2
0, 32...Mixer, 11, 14, 29, 31
......gate circuit, 13,30...oscillator, 25...comb filter.

Claims (1)

[Claims] 1. A luminance signal of a color television signal including a VIR signal is angularly modulated, a carrier color signal is low-pass converted and recorded while being superimposed on the angularly modulated wave, and the angularly modulated wave is used during playback. A color television signal recording and reproducing device that demodulates the carrier color signal into a luminance signal, converts the low frequency carrier color signal to obtain the original carrier color signal, and then adds it to the luminance signal via a comb filter. means for generating a continuous wave phase synchronized with a chroma reference signal of the VIR signal to be recorded;
means for superimposing the continuous wave on the carrier color signal to be recorded as a reconstructed chroma difference signal over a plurality of horizontal scanning periods of a vertical blanking period of a color television signal; and an output of the comb filter during reproduction. and means for replacing an oscillator output phase-synchronized with the reconstructed chroma difference signal obtained by the means with a reproduced chroma difference signal. A recording and reproducing device for color television signals. 2. The color television signal recording and reproducing apparatus according to claim 1, wherein the period in which continuous waves are superimposed is a horizontal synchronizing signal period.