JPS63166380A - Recording system for video signal - Google Patents

Abstract

PURPOSE:To eliminate moire due to so-called pseudo gap of a ferrite head by inverting the polarity during picture period only at each horizontal period, applying FM modulation and recording the signal. CONSTITUTION:The polarity inversion (multipliers 3W, 3N, 3Y) is applied in the amplitude direction at each horizontal period for only the picture period of a video signal and the video signal is recorded while being subject to FM modulation (circuits 5W, 5N, 5Y) in the recording system of the video signal. Thus, since the moire depends on the difference of the FM carrier, the signal is always demodulated at the positive polarity, and only the moire component is eliminated excellently by adding the inverted signal at the reproduction between adjacent scanning lines having the vertical correlativity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal recording system suitable for use particularly in high-definition VTRs.

[Summary of the invention]

The present invention relates to a video signal recording method, in which the polarity of only the image period is reversed every horizontal period and FM modulation is performed for recording, thereby making it possible to eliminate moire caused by the so-called pseudo gap of the ferrite head during playback. It is something to do.

[Conventional technology]

In the so-called high-definition V'l'11, it is considered to use a ferrite head because it handles short wavelengths and high frequencies. However, in the case of a ferrite head, the occurrence of pseudo gaps is unavoidable, which causes moire on the playback screen.

[Problem that the invention seeks to solve]

As described above, the conventional technology has problems such as occurrence of mo1 blur due to the pseudo gap of the ferrite head.

[Failure to solve the problem]

The present invention inverts the polarity of only the image period of the video signal in the amplitude direction every horizontal period (multiplier (3W) (3N) (3Y
)), and this video signal is subjected to i'M modulation (circuit (5W)
(5N) C5Y) ) This is a recording method for video signals.

[Effect]

According to this, since Moire V depends on the difference between FM carriers, it is always demodulated with positive polarity, and only the Moire component can be improved by adding the reversely inverted signals between adjacent scanning lines with vertical correlation during reproduction. Can be removed.

〔Example〕

In Figure 1, video signals of three primary colors, red (R), green (G), and blue (B), are supplied to the input terminal (IR) (IGOIB), and these signals are sent to the input terminal (IR) (IGOIB). A luminance signal Y and two color difference signals Cw and CN are formed. These signals Y, CW, and CN are sent to the multipliers (3
Y) (3W) (3N), and the polarities of the signals Y, Cw, and CN are inverted by a control signal corresponding to every other horizontal image period from the control terminal (4). Here, since the signals Cw and CN have an O level, polarity inversion is performed around this level. Further, for the signal Y, an arbitrary reference level may be set and polarity inversion may be performed around this level.

The signals from the multipliers (3Y) (3W) (3N) are respectively supplied to modulation circuits (5Y) (sw) (5N), subjected to FM conversion and recorded in a recording system (6) consisting of a tape head, etc. be done.

Recording is performed in this manner. Further, during playback, the signal from the recording system (6) is demodulated by g (7Y) (7
W) (7N) and demodulated by f''M, and these demodulated signals are respectively supplied to the multipliers (8Y) (8W) (sN) and are supplied to the terminal (4) from the control terminal (9). control signal or multiplier (sY) (sW
) (sN) to perform polarity inversion opposite to recording.

The signals from the multipliers (8Y) (8W) (8N) are transmitted through delay lines (IOY) (IOW) (IOW) of one horizontal period, respectively.
ON), the signal from this delay line and the original signal are added in the adder (11Y) (11W) (I IN), and this added signal is supplied to the matrix circuit 0z to add the original three primary colors. The video signal is sent to the output terminals (13R) (13G) (
13B).

Therefore, in the device shown in this figure, for example, the signal shown in FIG. 2A from the matrix circuit (2) is
The polarity of the image period of every other horizontal period is reversed by the control signal shown in FIG.
M modulated and recorded.

When this signal is reproduced and Fki demodulated, a mowa V occurs in the demodulated signal as shown in the figure.

However, in this case, as shown in the enlarged view of FIG. 3, this seven crack component has a frequency J1. This corresponds to the absolute value of the difference between J2, and therefore, regardless of the polarity of the video signal, if the difference in frequency is the same, the components are equal. Therefore, by adding the video signal of one horizontal period ago whose polarity has been inverted, the mo(flare component) can be removed and a video signal with doubled signal components can be obtained.

This allows each adder (IIY) (IIW) (IIN)
A video signal from which moiré components have been removed, as shown in FIG. 2E, is output from the device, and this signal can be used to obtain a good reproduced video signal.

Video signals are recorded and reproduced in this way, and since the above-mentioned recording method eliminates moire caused by pseudo gaps, a ferrite head can be used as the recording/reproducing head. , short wavelength, high frequency signals can be recorded and reproduced well.

Note that in the above recording method, the color difference signal Cw.

Since the O level exists in CN, polarity reversal can be easily performed, but in this case, by adding the reversed signal during reproduction, fluctuations in the DC level are also removed, and the hue and Stability of saturation etc. can be increased.

In addition, it is necessary to set an arbitrary reference level to invert the polarity of the bright signal Y, and in this case, it is necessary to transmit this reference level to the playback side, but if this is possible, the polarity of the three primary color signals can be inverted as is. You can also record it.

〔Effect of the invention〕

According to this invention, since moire depends on the difference between FM carriers, it is always demodulated with positive polarity, and only the moire component can be improved by adding the reversely inverted signals between adjacent scanning lines with vertical correlation during reproduction. Now it can be removed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an example of the present invention, and FIGS. 2 and 3 are waveform diagrams for explaining the same. (1) is the input terminal, (2) α2 is the matrix, t3+
+81 is a multiplier, +41 f9+ is a control terminal, +51 is an FM modulation circuit, (6) is a recording system, (l■ is a delay line, Oυ
is an adder, and 13] is an output terminal.

Claims (1)

[Claims] A video signal recording method in which the polarity of only the image period of the video signal is inverted in the amplitude direction every horizontal period, and the video signal is FM modulated and recorded.