JPS62252293A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To decrease a cross talk interruption occuring between the input and output of an FM modulating circuit by providing the first filter means to decrease the high area response of a luminance signal at the front stage of an FM modulating means and providing the second filter means to emphasize the low area of the FM modulating signal at the post stage of the FM modulating means. CONSTITUTION:An input video signal 1 comes to be a luminance signal component only by passing through an LPF 2, supplied through an emphasis circuit 4 to a low pass filter 17, high-area-suppressed, FM-modulated by an FM modulating circuit 5 and the side band wave component is level-decreased only by a high area suppression. Next, the signal is supplied to an FM low area emphasizing circuit 21 and a low area part is emphasized only by the characteristic of the low pass filter 17. Consequently, by the low pass filter 17, a luminance signal high area is suppressed by a base band, emphasized at an FM band by a low area emphasizing circuit 21 and a flat satisfactory frequency characteristic is obtained. Only for the part in which the high area part of the input signal to the FM modulating circuit 5 is suppressed and limited, the cross talk quantity of an FM low area component band-overlapped with a base band luminance signal occuring to the input from the output of the FM modulating circuit 5 is decreased.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a magnetic recording and reproducing device for recording and reproducing video signals on a magnetic storage medium such as a magnetic tape, and in particular, frequency modulation (hereinafter referred to as FM modulation) of a luminance signal during recording. The present invention relates to a magnetic recording and reproducing device suitable for improving the performance of FM modulation signal processing (abbreviated).

[Conventional technology]

As described in Japanese Patent Publication No. 53-45656, the conventional device performs FM modulation on the luminance signal of the video signal, converts the chroma signal into a low frequency band, and converts the chroma low frequency signal into the low frequency band of the luminance FM signal. Signals are frequency multiplexed and recorded on a storage medium.

In this case, the input and output signals of the circuit that performs FM modulation are unlikely to cause crosstalk with each other.To explain this using an image quality reproduction device as an example, in the same figure, the input signal 1 supplied to the input terminal has its luminance signal 3. Low pass filter (LPF) 2
The luminance signal is further supplied to the FM modulation circuit 5 via the emphasis circuit 4 and subjected to FM modulation. On the other hand, the chroma signal 7 extracted by the bandpass filter 6 (BPF) is frequency-converted by the low-frequency conversion circuit 8 to the lower side of the FM-modulated luminance signal band. Both of the above signals (FM luminance signal 14 and low frequency chroma signal 1)
5) The signals are added by the adding circuit 9 and then recorded on the magnetic tape 11 by the magnetic head 10.

Here, as is clear from FIGS. 5 and 6, the low frequency component of the FM luminance signal 14 and the high frequency component of the luminance signal 3 overlap in terms of band, and between the input and output of the FM modulation circuit 5. There was a problem in that both signals were likely to cause crosstalk, resulting in interference with image quality. especially! When the signal 12 of about 2M Flz of the luminance signal 3 shown in Fig. 5 is frequency modulated, the FM luminance signal is a carrier wave 16 (frequency is 4M
The first sideband component 13 of Hz) becomes the main component, and the signals 12 and 13 have almost the same band. Therefore, when the input signal 12 and the output signal 15 of the FM modulation circuit 5 crosstalk, the beat component becomes a low frequency band and causes a moiré pattern disturbance.

[Problem that the invention seeks to solve]

As described above, the above-mentioned conventional technology does not take into account crosstalk between the input and output of the FM modulation circuit, and has the problem of deterioration of image quality.

An object of the present invention is to provide a magnetic recording and reproducing device that can reduce image quality deterioration due to the above-mentioned crosstalk and improve the image quality of reproduced luminance signals particularly at frequencies where the luminance 1f signal and its FM modulated first sideband signal are very close in frequency. Our goal is to provide the following.

[Means for solving problems]

The above object is to provide a first filter means for reducing the high frequency response of the luminance signal before the FM modulation means, and a second filter means for emphasizing the low frequency response of the FM modulation signal after the FM modulation means. , 1 -.

[Effect]

The first filter means reduces the high-frequency components of the input luminance signal of the FM modulation means, but the second filter means reduces the high-frequency components of the input luminance signal by an amount corresponding to the high-frequency components of the input luminance signal.
The M modulation signal level is emphasized, and overall a flat frequency characteristic is reproduced.

In addition, the high-frequency component of the input luminance signal of the FM modulation means is reduced by the first filter means, and interference due to crosstalk between the input and output of the FM modulation means can be reduced by this amount.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG. 1st
In the figure, 17 is a resistance 18.19. A low-pass filter consisting of a capacitor jk20, 21 is a transistor 22°23,
Resistance 24-27. A low-pass filter WFM low frequency emphasizing circuit consisting of a capacitor 28, 29 indicates a power supply voltage line, and the same or equivalent parts as in FIG. 4 are given the same reference numerals.

Next, the operation will be explained using FIG. 2. The input video signal 1 becomes only a luminance signal component by passing through the LPF 2, and then passes through the emphasis circuit 4, which is placed before the FM modulation circuit 5 and has a low-pass frequency characteristic.

In the low-pass filter 17, the input signal of the low-pass filter 17 shown by 5 in Fig. 2(b) is subjected to high frequency suppression by the frequency tolerance shown in Fig. 2(a). 2
The signal shown at 9 is output. The signal 29 is subjected to FM modulation by the FM modulation circuit 5, and the sideband portion is reduced in level by the amount of high frequency suppression, resulting in a signal shown at 30 in FIG. 2(c). Next, the signal is supplied to an FM low frequency emphasizing circuit 21 arranged after the FM modulation circuit 5. In the low frequency emphasis circuit 21, after being amplified by the transistor 22, the resistor 25.
26 and a capacitor 28 (the input/output frequency characteristics are shown in FIG. 2(d)), the transistor 23. A signal is output by an emitter follower buffer consisting of a resistor 27. That is, 30 in Figure 2(e)
The output signal of the FM modulation circuit 5 shown in 2 has its low frequency portion emphasized by the low-pass filter characteristic shown in FIG. 2(d) of the low-frequency emphasis circuit 21, and is Outputs the indicated signal. Therefore, although the luminance signal band portion is suppressed in the QS band by the low-pass filter 17, it is emphasized in the FM band by the low-frequency enhancement circuit 21, and a flat and good frequency characteristic can be obtained as in the conventional case. In addition, the FM low frequency output of the FM modulation circuit 5 becomes smaller by the amount that the high frequency portion of the input signal to the FM f modulation circuit 5 is suppressed, so that a difference occurs from the output of the FM modulation circuit 5 to the input. The amount of crosstalk of the FM low-frequency component whose band overlaps with that of the paze-panned luminance signal is reduced, which has the effect of reducing deterioration due to crosstalk interference and significantly improving image quality.

@3 Figure shows another embodiment of the present invention, in which a low-pass filter 17. This is an example in which a lag-type low-pass filter is configured as the low-frequency emphasis circuit 21, and the same effect as the embodiment shown in FIG. 1 can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize a magnetic recording and reproducing apparatus that can reduce crosstalk interference occurring between the input and output of an FM modulation circuit and can significantly improve reproduced image quality.

[Brief explanation of drawings]

Figure 1 is a wiring diagram showing one embodiment of the present invention, Figure 2 (a)
~(e) is a characteristic diagram provided for detailed explanation of the present invention, Nf,
FIG. 3 is a circuit diagram showing another embodiment of the present invention, FIG. 4 is a block diagram showing a conventional example, and FIGS. 5 and 6 are characteristic diagrams for explaining the conventional example. 1... Input video signal 2... LPF3... Luminance signal 5... FM modulation circuit 6... BPF
7...Chroma signal 8...Low frequency conversion circuit
9...Addition circuit 10...Magnetic head 11...
・Magnetic tape 14...FM brightness signal 17...Low pass filter 21...Low frequency emphasis circuit! IA 1 Figure 20 Mo3 Garden L u Liu 4 (2) S Figure 1fl: i number (MHz) Ifll number (MHz)

Claims (1)

[Claims] 1. The input video signal is divided into at least two frequency bands (Y_
(L and Y_H); and means for frequency modulating the low frequency component (Y_L) of the divided video signal.
Magnetic recording comprising means for converting a high frequency component (Y_H) of the divided video signal to a low frequency, and means for adding each output of the frequency modulation means and the frequency conversion means and recording it on a magnetic storage medium. In the playback device, the above-mentioned low frequency component (Y
_L) first filter means for band-suppressing the high frequency part of the signal;
and second filter means for emphasizing the low-frequency components of the signal frequency modulated by the frequency modulation means, the first filter means being disposed upstream of the frequency modulation means, and the first filter means disposed before the frequency modulation means, and A magnetic recording/reproducing device characterized in that the second filter means is arranged at a rear stage.