JPH01105688A - Magnetic recorder for video signal by line sequential system - Google Patents

Abstract

PURPOSE:To prevent reproducting picture quality accompanying a dubbing from being lowered by selecting one color difference signal without fail based on a horizontal synchronizing signal after a prescribed period with a vertical synchronizing signal as a reference with a line sequential switch and the other color difference signal without fail based on the next horizontal synchronizing signal. CONSTITUTION:For a switching pulse PS1 which is a Q output of a D flip-flop circuit 31, a condition is changed based on the horizontal synchronizing signal after the prescribed period from the vertical synchronizing signal with this vertical synchronizing signal as the reference. After this prescribed period, a line sequential switch 6 surely selects only one color difference signal. For example, when the switching pulse PS1 is a high condition, the line sequential switch 6 selects a contact 6b and a color difference signal B-Y. Accordingly, even how many times the dubbing is executed, the color difference signal, which is allowed to be line sequential, is surely recorded by an original signal.

Description

[Detailed description of the invention] <Public funds for industrial use> The present invention relates to a magnetic recording device for video signals using a line sequential method, and is useful when applied to dubbing video signals recorded using a line sequential method. be.

<Prior Art> In France and other countries, a television sign system called the SECAM system has been standardized.

In this SECAM recording system, two color difference signals R-Y and B-Y are alternately switched and selected by a line sequential switch every horizontal scanning period (hereinafter abbreviated as IH period), and each is selected by two color difference signals R-Y and B-Y. The subcarrier is frequency modulated and superimposed on the luminance signal to form a carrier video signal.

On the other hand, in the reproduction system, a color difference signal that is delayed by an IH period (hereinafter referred to as an interpolated signal) and a color difference signal that is not delayed (hereinafter referred to as an original signal) are taken out in parallel, so that the color difference is thinned out every IH period. Two types of continuous color difference signals RY and BY are obtained by supplementing the signals RY and BY.

For this reason, the reproduction system generally requires a switch for alternately extracting the interpolated signal and the original signal. Taking out color difference signals of type 281 in parallel in this way is called synchronization, and a switch for this purpose is called a synchronization switch.

FIG. 3 is a block diagram showing an example of a recording system in the SECAM system. As shown in the figure, in this example, an NTSC video signal is supplied to the input terminal 1. The baseband luminance signal of this video signal is separated from the sub-carrier color difference signal by a Y/C separation circuit 2 and supplied to an FM modulator 3 and a synchronization separation circuit 4. On the other hand, the sub-carrier color difference signal is demodulated by the WAL unit 5 and supplied to the line sequential switch 6 as two types of baseband color difference signals R-Y and B-Y. be converted into

That is, the line sequential switch 6 receives the switching pulse Pst
Contact 6a alternately every IH period.

6b, and select one of the color difference signals R-
Select Y, B-Y. The line-sequential color difference signal (R-Y) 1°<B-y) obtained in this way is FM modulated by the FM modulation N7 and becomes a carrier color difference signal, which is sent to the mixer 8.
At this vibration M8, it is multiplexed with the carrier luminance signal, which is the output signal of the FM modulator 3, to become a carrier video signal, which is then passed through the recording amplifier 9 and sent to the magnetic recording medium (not shown) by the recording head 0. ) will be recorded.

The switching pulse P□ is a signal formed by the switching pulse circuit 11 based on the horizontal synchronizing signal separated by the synchronizing signal separation circuit 4, and is generated by IH in synchronization with the horizontal synchronizing signal.
This is a pulse signal that repeats an H (high) state and an L (0-) state every period.

FIG. 4 is a block diagram showing an example of a reproducing system corresponding to the above recording system. As shown in the figure, a reproducing head 12 reproduces a conveyed video signal recorded on a magnetic recording medium by the recording system shown in FIG. This carrier video signal is supplied to a bypass filter 14 and a low-pass filter 15 via a head amplifier 13. Bypass filter 1
4, the carrier luminance signal is extracted from the carrier video signal and the FM
ll regulator 16. As a result, a luminance signal Y is obtained as an output signal of the FM demodulator 16. On the other hand, the carrier video signal and the carrier color difference signal are extracted by the pass filter 15 and supplied to the FMg modulator 17. As a result, the output signal of the FM demodulation book 17 is a line sequential color difference signal (RY input, (
Obtain BY input. This line sequential color difference signal (RY).

(B − Y ), one of which is demodulated before the IH period and I
It is applied to the synchronization switch 19 at the same time as the other signal delayed by the H period delay circuit 18. The synchronization switch 19 includes a switch 20 that outputs a synchronized color difference signal (R-Y), and a switch 21 that outputs a synchronized color difference signal (B-Y). The switch 20 has contacts 20a and 20b, and the switch 21 has contacts 21m and 2
1b, and the contact 20a and the contact 21b are
In addition, so that the contact 20b and the contact 21a are selected simultaneously, the switch 20 is directly activated by the switching pulse P62, and the switch 21 is inverted by the inverter 22 so that the I
It is switched every H period. Contact points 20m and 21a are IH
line-sequential color difference signal (R-Y) l delayed by a period;
(B-Y) 1 is also the contact point 20b.

21b contains the line-sequential color difference signal (
RY), , (B-Y), are supplied, respectively. Synchronized color difference signal (R=Y) synchronized by the synchronization switch 192. (B - Y )2 is supplied to the quadrature two-phase balanced modulator 23, and this quadrature two-phase balanced modulation -23
Simultaneous color difference signal (R-Y) 2. (B-Y), two types of carrier waves are balanced-modulated, and the thus obtained 2N-order simultaneous carrier color difference signal (R-Y)3. (BY)3 is mixed. Simultaneous carrier color difference signal (R-Y)3. (B-
Y)3 is supplied to a mixer 924, where it is combined with the luminance signal Y to become a standard video signal of the NTSC system, and this video signal is outputted via the output terminal 25. - The switching pulses P and 2 are line sequential color difference signals (R-
Y), , (B-Y), and a signal formed by the switching pulse ii@27 based on the horizontal synchronization signal separated from the luminance signal Y by the synchronization signal separation circuit 26, and IH in synchronization with the horizontal synchronization signal. This is a pulse signal that repeats an H state and an L state every period.

In the line sequential method, the color difference signal R-Y is generated on the reproduction side.

Various efforts have been made to identify B7Y. One method is to make the modulation frequencies of the line sequential color difference signal (R-Y) 1 and the line sequential color difference signal (B-Y) different during recording.

In this example, (RY)i modulates a higher frequency carrier. Therefore, the line sequential color difference signal (RY) t after being demodulated by demodulation l#17.

(B-Y), is sampled by the horizontal synchronization signal, and line sequential color difference signals (R-Y),, (B-Y) are obtained.

When the level of the blanking period is clamped, the line sequential color difference signal (RY) has a higher level. This changes the H state of the switching pulse P@Q to (R-
Y), , and L states can be made to correspond to (B - Y), respectively, and when the switching pulse P is in the H state, the contact 20b.

If the contacts 20m and 21b are selected in the 21aSL state, RY can be taken out through the switch 20, and B-Y can be taken out through the switch 21, respectively.

FIGS. 5(a) to 5(f) are explanatory diagrams conceptually showing the structure of the luminance signal Y and each color difference signal in the line sequential method. In the figure, the subix attached to Y indicates the number of the horizontal scanning line to which the color difference signals R-Y and B-Y belong, and 1
The four boxes indicate the IH period.

FIG. 5(a) shows the luminance signal Y. The color difference signals FL-Y and B-Y shown in FIG. 5(b) and FIG. 5(0) are alternately selected by the line sequential switch 6 for each IH period to form the line sequential signal shown in FIG. 5(d). chrominance color difference signal (R-Y), ,
(B-Y). Line sequential color difference signals (R-Y), , (B-Y) in this case.

is the odd number for the color difference signal R-Y, and the color difference signal B-
Regarding Y, those belonging to even-numbered IH periods are selected. Such line sequential color difference signal (1'L-Y)8. (B
-Y)- On the color reproduction side, those delayed by the IH period and those not delayed by the IH period are synchronized by the synchronization switch 19, resulting in two types of simultaneous color differences shown in FIG. 5(e) and FIG. 5(f). The signals become (RY), , (B-Y).

In such a line-sequential system, as is clear from FIG. 5(・) and FIG.
-Y) 2 is an even-numbered signal, and the simultaneous color difference signal (B
-Y), the signals belonging to odd-numbered IH periods are line sequential color difference signals (R-Y), , (B-Y
), is obtained by delaying the signal by 1m (period).In other words, for the synchronized color difference signal (R-Y), the signal belonging to the odd-numbered IH period is the original signal, and the signal belonging to the even-numbered IH period The signal is an interpolated signal.

The relationship is the opposite for the simultaneous color difference signal (B - Y).

<Problems to be Solved by the Invention> By the way, when a video signal recorded by the line sequential method as described above is dubbed by the same method, the line sequential color difference signal (R-Y), (B -Y) may be shifted backward by the IH period from the horizontal scanning line to which it originally belongs.

This means that the video signal recorded by the line sequential method is
An example of dubbing using the recording/reproducing system shown in FIGS. 3 and 4 will be described.

As shown in FIGS. 5(e) and 5(f), the simultaneous color difference signals (R-Y), , (B-Y) are signals in which the original signal and the interpolated signal are repeated every IH period. . Therefore, when one of the interpolation signals of the simultaneous color difference signal (R-Y) and 2° (B-Y) is selected during line sequentialization in the recording system associated with dubbing, this line sequential A line sequential color difference signal (R-Y) formed by
(B-Y)t should be formed entirely of interpolated signals, as shown in FIG. 5(g). That is, in this case, all the elements of the line sequential color difference signals (R-Y), (B-Y) move backward by the IH period.

At the time of line sequentialization accompanying dubbing, only the interpolation signal is selected (i.e., the line sequential color difference signal (R-Y) t as shown in FIG. 5(2)) as described above.

The probability of forming (B - Y)l is a bar.

This is due to the following reason. That is, the recording system switching pulse P□ shown in FIG. Therefore, each IH period synchronized with the horizontal synchronization signal
Although it is a pulse signal that repeats the state and L state,
The line sequential switch 6 controlled by this switching pulse Pat selects which of the simultaneous color difference signals (R-Y
), .

(B - Y), it is uncertain whether to select it. At first,
If one original signal is selected, the other original signal is selected and line-sequentialized, but in the opposite case, interpolated signals are selected for both, and the interpolated signal generates a line-sequential color difference signal (R-Y). ,(
B-Y).

is formed.

Therefore, the probability of selecting only the interpolated signal during line sequentialization accompanying dubbing is 4, but in the worst case, the line sequential color difference signal (R-Y) 1# (
B-Y) 1 moves backward.

By the way, IIi! A line-sequential color difference signal (R-Y) recorded by line-sequentializing only the interpolated signal during eye dubbing.
(B - Y), when reproduced in a synchronized manner, the synchronized color difference signal (Ry) 2p (Fly) resulting from this synchronization is obtained, as shown in FIG. 5(h).

Since the original signal of is an interpolation signal for the first original signal, I
After the H period (IH or 2 on the played TV screen)
At the same time, as shown in FIG. 5(i), since the interpolated signal at this time is an interpolated signal of the interpolated signal for the first original signal, it also shifts backward in the 2H period. That is, only the color components of the video signal are shifted. For this reason,
When the recording system shown in FIG. 3 is used, there is a drawback that there is a possibility that the quality of the reproduced image will deteriorate as a result of dubbing.

In view of the above-mentioned prior art, the present invention has been developed so that even when a video signal recorded by a line sequential method is synchronized and reproduced, and then is line sequentially recorded again after it has faded, the line sequential signal to be recorded consists only of the original signal. An object of the present invention is to provide a magnetic recording device for video signals using a line-sequential method.

Means for Solving the Problems〉 The configuration of the present invention to achieve the above object is to alternately select two types of color difference signals by switching the switching pulse every one horizontal scanning period (by means of a line sequential switch that can be switched). In a magnetic recording device for video signals using a line-sequential method that performs line-sequential recording, a switching pulse is generated in which the gloss state changes based on a horizontal synchronization signal after a predetermined period from the vertical synchronization signal. and a line sequential switch that selects one color difference signal when the switching pulse is in one state and selects the other color difference signal when the switching pulse is in the other state.

(Function) According to the present invention having the above configuration, the line sequential switch that alternately selects one color difference signal and the other color difference signal for each horizontal scanning period is configured to perform a line sequential switch that alternately selects one color difference signal and the other color difference signal after a predetermined period based on the vertical synchronization signal. One color difference signal is always selected based on the horizontal synchronization signal, and the other color difference signal is always selected based on the next horizontal synchronization signal.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.The same parts as those of the prior art shown in FIG.

As shown in FIG. 1, the switching pulse times $28 in this embodiment are generated by the low-pass filter 29# comparator 30.
It consists of a D7 lip-flop circuit 31 and a 1H killer circuit 32. The a-pass filter 29 extracts a vertical synchronization signal from the composite synchronization signal (a synchronization signal consisting of a horizontal synchronization signal and a vertical synchronization signal) separated from the luminance signal by the synchronization signal separation circuit 4. It is a road. In other words, when the width is wide and the repetition frequency is low, such as a vertical synchronization signal, it contains relatively low frequency components, and when the width is narrow (the horizontal synchronization signal with a high repetition frequency contains high frequency components, it is an integrating circuit. A vertical synchronization signal is obtained by removing frequency components higher than a certain frequency through a low-pass filter 29.The rise and fall of the vertical synchronization signal extracted by this four-pass filter 29 are blunted; The waveform is shaped by passing the signal through the comparator 30.Thus, the vertical synchronization signal output from the comparator 30 has a slight delay Δt due to the characteristics of the stomach-pass filter 29, but the vertical synchronization period The pulse-signal P completely matches the D flip-prop circuit 31.
is serrated at the rising edge of the pulse signal P. The TH killer circuit 32 is a circuit for extracting only the pulses of each IH period from the composite synchronizing signal with the horizontal synchronizing pulse as a reference. More specifically, the components of the composite synchronization signal include equivalent pulses and vertical synchronization pulses, and since these also have pulses with a TH period, the IH period is used as the period with the horizontal synchronization pulse as a reference. It is designed to extract only the
This is achieved by taking an AND condition between the inverted output of the one-silicon multivibrator and the composite synchronization signal, which satisfy the condition H<T<IH. Therefore, the switching pulse P which is the Q output of the D flip-flop 51111
. The state changes based on the horizontal synchronizing signal after a predetermined period from this vertical synchronizing period with the vertical synchronizing signal as a reference, and the line sequential switch 6 always selects only one color difference signal after this predetermined period.

FIGS. 2(a) to 2(g) are waveform diagrams showing waveforms of various parts of the apparatus shown in FIG. 1. Of these, Figure 2 (a)
, (b) is a composite luminance signal consisting of a luminance signal and a synchronization signal separated from the 11 carrier color difference signal by the Y/C separation circuit 112, and is supplied to the synchronization signal separation circuit 4. In addition, Fig. 2 (a) shows the signals of the odd field, and Fig. 2 (b) shows the signals of the even field, where a is the equivalent period before the vertical synchronization period, and C is the equivalent period after the vertical synchronization period. It is a period. FIG. 2(e) shows a pulse signal P obtained by extracting a vertical synchronization period by a low-pass filter 29 and having its waveform shaped by a comparator 30. FIG. 2(d) shows that the horizontal synchronizing pulse, equivalent pulse, and cutting pulse are separated from the brightness signal of the odd field shown in FIG. 2(a), and the TH killer time is 1s32.
Based on the horizontal synchronization signal and the signal obtained through the drive pulse (odd field driving pulse HD representing the IH period), Figure 2 (•) shows the even field luminance signal shown in Figure 2 (b). 2(f) and 2(g) show the even field driving pulse HD obtained by the pulse signal P and the odd field switching pulse P obtained by the odd field Il!lWb pulse HD.
and the pulse signal pl and am field I! 111!
This is an even field switching pulse Ps1 obtained by the b pulse HD.

Referring to FIG. 2(f) and FIG. 25(g), it is clear that the switching pulse P□ falls at the fourth drive pulse HD from the rising edge of the pulse signal P in this example)J , becomes a pulse signal whose state changes every IH period.

The line sequential switch 6 has switching pulses P and L of “1”.
” (high) state, the contact 6a is selected to select the color difference signal hole -Y, and when the "0" (field) state, the contact 6b is selected to select the color difference signal B-Y. That is, Odd-numbered drive pulse HD counting from the beginning of the vertical synchronization period
Based on (when the switching pulse P□ is in the “1” state, the color difference signal RY is selected, and similarly, the switching pulse Psl based on the even-numbered drive pulse HD is “1”).
0'' state, the color difference signal B-Y is selected.

When dubbing using the device of this embodiment,
The output terminal 25 of the reproduction system shown in FIG. 4 and the input terminal 1 of the apparatus of this embodiment shown in FIG. 1 may be connected. At this time,
The line sequential switch 6 of the recording system shown in FIG. 1 always selects only one color difference signal after a certain period of time based on the vertical synchronization signal, so no matter how many times you dub, the line sequential switch 6 of the recording system always uses the original signal. The color difference signals obtained are recorded.

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, according to the present invention, the S
During sequentialization, the type of color difference signal that is selected after a predetermined period based on the vertical synchronization signal is determined, so even if the video signal reproduced by synchronizing the original signal and interpolation signal is dubbed, the original signal will not be reproduced. It is possible to obtain a color difference signal in which only the signal is line-sequential, and there is no deterioration in image quality due to dubbing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 (
a) - 2nd ffiigl are waveform diagrams showing the waveforms of each part; FIG. 3 is a block diagram showing a recording system according to the prior art;
Figure 4 shows the block diagram 111 showing the reproduction system, and Figure 5 (
a) to FIG. 5(i) are explanatory diagrams conceptually showing the configuration of a luminance signal and a color difference signal in the line sequential method. In the drawing, 6 is a line sequential switch, 2B is a switching pulse circuit, 29 is a four-pass filter 30 is a comparator, 31 is a D flip-flop circuit, 32 is a TH killer circuit, Pl is a pulse signal, HD is a drive pulse, P is a switching pulse. Procedural amendment (method) February 17, 1988

Claims (1)

[Claims] In a magnetic recording device for video signals using a line-sequential method, in which two types of color difference signals are alternately selected by a line-sequential switch that is switched every horizontal scanning period by a switching pulse, and recorded in a line-sequential manner, a vertical synchronization signal is used as a reference. a switching pulse generation circuit that generates a switching pulse whose state changes based on a horizontal synchronization signal after a predetermined period from the vertical synchronization signal; 1. A magnetic recording device for a video signal using a line sequential method, comprising a line sequential switch that selects the other color difference signal when .