JPS5850076B2 - Color video signal recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a vertical blanking period reference signal (VerticalIn
Terval Reference Signal:
The present invention relates to a recording and reproducing apparatus for color video signals including VIR signals (hereinafter referred to as VIR signals).

Conventionally, in color video signal recording and reproducing devices such as helical scan type color video tape recorders, a comb filter including an IH delay line is used in the color signal processing system in order to improve the S/N ratio of the reproduced color signal. Similar comb-shaped filters were used to remove crosstalk between adjacent tracks of color signals.

Further, a similar comb filter has been used for the purpose of removing cross color components of the NTSC color video signal itself.

These comb filters utilize the H correlation (H: horizontal scanning period) of the color signal, so the 19
There was a drawback that the VIR signal inserted only at the Hth position was disturbed.

There is a drawback that the VIR signal is disturbed by mere crosstalk between adjacent tracks.

Furthermore, since the carrier color signal including the VIR signal is converted to a low frequency band and the frequency-modulated luminance signal is recorded as a bias signal, there is a drawback that the S/N ratio of the reproduced VIR signal is poor.

When a color video signal containing such a disturbed VIR signal or a color video signal containing a VIR signal with a poor S/N ratio is supplied to a color television receiver configured to automatically adjust the hue using the VIR signal, the above-mentioned problem occurs. There was a problem with color television receivers malfunctioning.

The present invention prevents the malfunction of a color television receiver as described above by converting the VIR signal into a color video signal that does not contain the VIR signal in the process of recording or reproducing the color video signal that includes the VIR signal. The present invention provides a color video signal recording and reproducing device.

Hereinafter, the present invention will be explained with reference to drawings of embodiments.

FIG. 1 is a block diagram of essential parts of an embodiment of the present invention.

As shown in the figure, the color video signal applied to the input terminal 1 is supplied to the low-pass filter 2 button and the bandpass filter 7.

The output of the low-pass filter 2 is supplied to an adder 6 via a delay circuit 3, an FM modulator 4, and a high-pass filter 5.

On the other hand, the output of the bandpass filter 7 is supplied to a low-pass filter 10 via a balanced modulator 8 to which an oscillator 9 is connected, and its output is supplied to the adder 6.

The output of the adder 6 is, for example, a well-known rotating magnetic head,
Recording/playback system 1 including magnetic tape as a recording medium
1 and recorded.

Next, the reproduction output from the recording/reproduction system 11 is supplied to a high-pass filter 12 and a low-pass filter 17.

The output of the high-pass filter 12 is supplied to a counting circuit 14 and an adder 15 via an FM demodulator 13.

The output of the adder 15 is supplied to the output terminal 22 via a gate circuit to which the counting circuit 14 is connected.

These counting circuit 14 and gate circuit 16 constitute a signal processing means.

On the other hand, the output of the low-pass filter 17 is connected to a bandpass filter 20 via a balanced modulator 18 to which an oscillator 19 is connected.

The output of the bandpass filter 20 is then supplied to the adder 15 via a comb filter 21.

Next, the operation of this embodiment will be explained with reference to the signal waveform diagram of each part in FIG. 2.

The input terminal 1 has an NTSC cable as shown in Fig. 2A.
A color video signal is given.

Note that the numbers written at the top of the waveform shown in Figure 2 indicate that the horizontal scanning period H at the beginning of the field (beginning of the equalization pulse) is 1.
The second one? Indicates the CH number.

FIG. 2A shows that the VIR signal is inserted at the 19th H.

The same goes for the next field.

Note that the normal video signal starts around the 22nd H.

A color burst signal is inserted after the horizontal synchronization signal in Hs other than the H including the truncated equalization pulse and the vertical synchronization signal (fH to 9H in the above number).

This color video signal is applied to the low-pass filter 2 button and the bandpass filter 7.

The luminance signal, which is the output of the low-pass filter 2, is delayed by the time difference from the carrier color signal in the delay circuit 3, and then FM-modulated in the FM modulator 4.

Further, low frequency components of the frequency of 1 MHz or more are removed by a pass band filter 5 and added to the adder 6.

For example, if the band of the luminance signal is set to 0 to 2.4 MHz, F
If the M frequency deviation is 3.4 to 4.4 MHz, the occupied band of the lower side wave and the FM carrier is IMHz to 4.4 M
It becomes Hz.

On the other hand, the carrier color 55 signal, which is the output of the bandpass filter 7, has a color subcarrier frequency (fs = -fH1, where fH:
It has a band of ±500 KHz centered around the horizontal scanning frequency).

FIG. 2B shows an output waveform diagram of the bandpass filter when the input signal is as shown in FIG. 2A.

This carrier color signal is subjected to low frequency conversion in the balanced modulator 8 using a carrier having the frequency fa of the oscillator 9.

If the frequency fa of this oscillator 9 is selected as fa55 = (-+ 40) fH, the output of the low-pass filter 10 has a frequency band of 40 fH ± 500 KHz.
A low-pass converted carrier color signal is obtained.

The output waveform of this low-pass filter 0 is the same as that in FIG. 2B, with the only difference being the frequency.

Such a carrier color signal is frequency-multiplexed with the FM-modulated luminance signal by the adder 6, and then sent to the recording/reproducing system 11.
recorded and played back.

Note that the recording/reproducing system 11 can use a well-known rotating magnetic head/drum device used in video tape recorders, so a detailed explanation will be omitted here.

Next, the signal reproduced from the recording/reproducing system 11 is 1MH.
The FM-modulated luminance signal is extracted by supplying it to the high-pass filter 2 whose normal band is above z.

This FM-modulated luminance signal is demodulated into the original luminance signal by the FM demodulator 13.

This luminance signal is supplied to the counting circuit 14 and adder 15.

At the output terminal of the counting circuit 14, there is a terminal as shown in FIG. 2C.
A pulse signal P1 is obtained which is at Low level only after the 9th fixed time, that is, after the burst flag position, and is High during all other periods.

On the other hand, the signal reproduced from the recording/reproducing system 11 is
By supplying the signal to the low-pass filter 7 whose passband is below MHz, the original low-pass converted carrier color signal can be obtained.

This low-pass conversion carrier color signal is frequency-converted by the balanced modulator 18 using the output signal of the oscillator 19, unnecessary frequency components are removed by the bandpass filter 20, and noise components or track signals are removed by the comb filter 21. The crosstalk components are removed to obtain a carrier color signal as shown in the second diagram.

The output signal of the oscillator 19 and the configuration of the comb filter 21 will be described later.

However, as shown in the second diagram, the chrominance reference signal in the VIR signal included in the carrier color signal is
Since there is no correlation, the signal is divided into the 19th H and 20th H, and the level thereof is 1/2 of the original signal.

The carrier chrominance signal containing the VIR signal thus disturbed is frequency-multiplexed by the adder 15 onto the luminance signal which is the output of the FM demodulator 13, and the gate circuit 16 has an NTSC signal as shown in FIG. 2E. A color video signal is supplied.

Here, since the gate circuit 16 outputs only the period when the pulse signal P1 from the counting circuit 16 is High, the output terminal 22 has a disturbed VIR as shown in FIG.
An NTSC color video signal with the signal removed is obtained.

Next, the output signal of the oscillator 19 will be explained.

This signal is used to correct time axis fluctuations (so-called jitter) that the carrier color signal receives in the recording/reproducing system 11.

The frequency of this signal is approximately the same as the oscillation frequency fa of the oscillator 9, and has time axis fluctuations that are in opposite phase to the time axis fluctuations described above.

The crosstalk components between adjacent tracks of the carrier chrominance signal which is twisted and transmitted to the recording/reproducing system 11 are configured to have a frequency interleaved relationship with the frequency spectrum of the carrier chrominance signal, and the crosstalk components are interleaved with the frequency spectrum of the carrier chrominance signal. For example, the phase of the carrier of the frequency fa of the oscillator 9 is removed by the filter 21.
Set the appropriate size in 0' increments, 9 for each IH in the (n+1) field.
Recording is performed with a delay of 0 degrees, and during reproduction, the phase of the output signal of the oscillator 19 is delayed by 90 degrees, or the phase of the carrier of the frequency fa of the oscillator 9 is inverted every IH in the n fields, and (n+1) The field is recorded without inversion, and during playback, the phase of the output signal of the oscillator 19 is inverted every IH in the n fields, and (n+1
) It is acceptable to use a method that does not invert in the field.

However, n is any integer. Next, the configuration of the comb filter 21 will be explained.

As illustrated in FIG. 3, this comb filter 21 has an I
H delay line (in this case IH stands for time and I
H = 63.556μ5ec) 23 and difference calculation circuit 24
It is made up of.

Its frequency characteristics are as shown in FIG. 4, and components having a frequency interleaving relationship with the carrier color signal, that is, components having a frequency of m.times.f.sub.H (where m is an arbitrary integer) are removed.

For example, the above-mentioned crosstalk component between adjacent tracks or the frequency generated in the above-mentioned recording/reproduction system 11 is m
Remove the noise component that is fH.

However, when there is information only in one horizontal scanning period like the VIR signal, the level of the information becomes 1/2 and spreads over two horizontal scanning periods, as is clear from the configuration of the comb filter 21.

Furthermore, if the information of the previous and subsequent horizontal scanning periods is different, they are calculated and the information becomes disordered.

Note that instead of removing only the 19th H as described above, several H before and after the 19th H may be removed.

In this case, it is desirable to remove the video signal portion excluding the horizontal synchronization signal and burst signal.

In addition, in FIG. 1, the counting circuit 14 and the gate circuit 1
Although the embodiment has been described in which the signal processing means consisting of 6 is applied to the reproduction side signal processing system, the same applies even if it is applied to the recording side signal processing system.

Furthermore, although FIG. 1 shows an embodiment in which the 19th H is removed from a signal in which a carrier color signal is multiplexed with a luminance signal, it is practically acceptable to remove it from the luminance signal before multiplexing.

As described above in detail, the color video signal recording and reproducing apparatus of the present invention is capable of generating a signal even if a VIR signal is disturbed by, for example, a comb filter used in a color signal processing system.
In order to convert the signal into a color video signal with the signal removed, VIR
Even if the color video signal is supplied to a color television receiver having a function of automatically adjusting the hue using the signal if there is a signal, the color television receiver does not malfunction because it determines that there is no VIR signal. , it has the feature of working normally.

Note that the present invention is not limited to color video tape recorders;
It goes without saying that the present invention can also be applied to magnetic, optical, mechanical or mechanical recording and reproducing devices using disc-shaped recording media.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a main part showing an embodiment of a color video signal recording/reproducing apparatus of the present invention, and FIGS. 2A and 2B. C, D, E, and F are signal waveform diagrams of each part in FIG. 1, FIG. 3 is a block diagram showing an example of the configuration of a comb filter, and FIG.
The figure is a diagram of its frequency characteristics. 11... Recording/reproduction system, 14... Counting circuit, 15... Gate circuit, 21...
Comb filter.

Claims (1)

[Scope of Claims] 1. A device for recording and reproducing color video signals, comprising a signal processing means for removing at least a vertical blanking period reference signal portion included in the color video signal. Device. 2. The signal processing means includes a counting circuit that counts the composite synchronization signal commonly included in the color video signal and outputs a pulse having a time width corresponding to at least the vertical blanking period reference signal portion;
2. The color video signal recording and reproducing device according to claim 1, further comprising a gate circuit for controlling opening/closing of transmission of the color video signal in response to the output of the counting circuit. 3. The color video signal recording and reproducing apparatus according to claim 1 or 2, wherein the signal processing means is provided in the recording side signal processing system. 4. The color video signal recording and reproducing apparatus according to claim 1 or 2, wherein the signal processing means is provided in the reproduction side signal processing system.