JPS63115492A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To minimize the beats of chrominance components and an FM signals and to reduce color smears and color shading while a high resolution is maintained by providing a recording amplifying part with a circuit correcting the phase characteristics of the chorominance components as well as a circuit correcting the frequency characteristic of a conventional FM signal. CONSTITUTION:An HPF 1 removes the low frequency of the recorded FM signal. In order to hold a high resolution at the time of reproduction, the HPF 1 is designed to have a cut-off below about 1 mHz and to pass through a far lower side band. Next an LPF 2 passing through the chrominance components is designed to have a relatively narrower band and the sharpest cut-off and to prevent the interference beat of the FM signal. A mixing circuit 3 makes the FM signal and chrominance components passing through the filter 1 and 2 into mixed signals, and the frequency characteristic correction circuit 4 makes them into FM signals with the frequency characteristics of optimum recording currents. The phase characteristic correction circuit 9 corrects the phase characteristics of the chrominance components passing through the LPF 2 having a narrow band and the sharpest cut-off, and compensates phase information that the LPF 2 damages.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in video signal processing in recording and reproduction of a helicopter-powered Lunecan type video tape recorder (hereinafter referred to as a VTR).

[Conventional technology]

FIG. 8 is a block diagram showing a conventional example.
(1) is a high-pass filter (hereinafter referred to as HoP) for removing the low frequency range of the FM-modulated luminance signal.

(2) is a low-pass filter (hereinafter referred to as P) for removing the high range of the low-pass converted color signal.

(3) is a mixing circuit that mixes the above-mentioned FM modulated luminance signal and low frequency conversion color signal, (4) is a mixed FM
Frequency characteristic correction circuit for correcting the frequency characteristic of the signal (5
) is an amplifier circuit for writing on the magnetic tape (8), (6
) is a rotary transformer for passing current through the magnetic head, and (7) is a magnetic head.

Next, the operation will be explained. Here, VH3 system VTR
will be explained using an example. FM modulated luminance signal (hereinafter referred to as FM signal) and low frequency converted color signal (hereinafter referred to as FM signal)
The frequency allocation of the chrominance signals (referred to as color signals) is as shown in FIG. In a HiFi VTR for deep audio recording, an audio FM signal (hereinafter referred to as an audio signal) exists in the deep layer. HlP, F(1) is for removing the low frequency portion of the FM signal and leaving a sufficient band for the color signal. The color signal band is 0.629MH2±500KH2
Since it has H, P.

F(1) uncut off frequency approximately IMHz, L,
P, F (2) + 7) W range approximately 1.1MHz
~1.2MH2 tonal. As mentioned above, P.

The FM signal and color signal that have passed through F(2), H, P, and F(1) are mixed by a mixing circuit (3), and a frequency characteristic correction circuit (4) outputs a signal to a magnetic head (7) at each frequency.
) and the tape (8) system, the frequency characteristics are corrected to obtain the optimum recording current, and the recording current is amplified in the amplifier circuit (5).
The rotary transformer (6) converts the stain pressure into sound flow,
A current is passed through the magnetic head (7) to record a video signal on the magnetic tape (8).

[Problem that the invention seeks to solve]

The conventional circuit is configured as described above, and the frequency allocation is as shown in Figure 4, but the FM signal recorded here is lowered to improve the resolution and frequency characteristics of the video signal during playback. The sidebands on the sides must be recorded as much as possible, and the cutoffs for H, P, and F (1) must be extended. In addition, the color signals are L, P, F to suppress color bleeding and color unevenness during playback.
(2) A sufficient bandwidth must be provided. Therefore,
Interference between the color signal and FM signal occurred, resulting in beats, etc. 9
Or, if beats are prevented from occurring, problems such as reduced resolution, color bleeding, color unevenness, etc. occur.

This invention is intended to solve the above problems.
[Means for Solving the Problems] A magnetic recording/reproducing device according to the present invention aims to suppress beats, reduce color bleeding, and color unevenness while maintaining high resolution of images. This circuit is provided with a circuit that not only corrects the frequency characteristics of the conventional FM signal but also corrects the phase characteristics of the color signal.

[Effect]

The magnetic recording/reproducing device of the present invention improves the band shortage and phase distortion of the color signal recorded in a small amount in the phase characteristic correction circuit, suppresses color bleeding and color unevenness, and prevents beats due to interference between FM signals and color signals. This allows you to obtain high-quality video signals with high resolution and less color unevenness and color blurring during playback.

〔Example〕

An embodiment of this invention will be described below. In FIG. 1, the configuration is basically the same as that of the conventional circuit in FIG. 8 up to the frequency characteristic correction. The difference from Fig. 8 is that the mixed signal of the FM signal and color signal that has undergone frequency characteristic correction is corrected for the phase characteristic of the color signal by the phase characteristic correction circuit (9).
6),? The point is that the data is recorded on the magnetic tape (8) by the AK head (7) in the same manner as in the prior art.

A specific example of the phase characteristic correction circuit (9) is shown in Fig. 2. In Fig. 2, QO and 0η are buffer amplifiers, (2) is an equalizer circuit for frequency characteristic correction, and 0 is a resonance circuit for phase characteristic correction. The circuit, α, is a transistor.

In such a configuration, the recorded FM signal is H, P
, F (1) removes the low frequency range, but this Ho
In order to maintain high resolution during playback, P and F (1) are filters that have a cutoff below about IMH2 and allow sufficiently lower sidebands to pass through. Next, L, P, and F (2), which pass the color signal, have a slightly narrow band (approximately IMH2) than conventional ones, and have as sharp a cutoff as possible to avoid beats that interfere with the FM signal. filter. Such a filter fil,
The FM signal and color signal that have passed through (2) are transferred to a mixing circuit (3)
The frequency characteristic correction circuit (4) generates an F having the frequency characteristic of the optimum recording current as in the prior art.
This becomes the M signal. The phase characteristic correction circuit (9) corrects the phase characteristic of the color signal that has passed through L, P, and F (2) which have a narrow band and a sharp cutoff.

Compensate for the phase information lost in P, F (2). Thereafter, the information is recorded on a magnetic tape (8) by a magnetic head (7) via an amplifier circuit (6) and a rotary transformer (6) as in the prior art.

Here, to explain a specific example of the phase characteristic correction circuit shown in FIG. )have.

The above-mentioned correction can be achieved by setting the resonance point of the resonance circuit 0 and C to a frequency for correcting the phase of the color signal.

In the above embodiment, the case where only the phase characteristic of the color signal is corrected has been explained, but the same effect as in the above embodiment can be obtained even if not only the phase characteristic of the color signal but also the frequency characteristic is corrected. is obtained.

〔Effect of the invention〕

As described above, according to the present invention, by providing a color signal phase characteristic correction circuit, the beats of the color signal and FM signal, which had been a problem in the past, can be suppressed to the minimum level and high resolution can be maintained! This has the effect of providing a high-quality reproduced video signal with less color bleeding and color unevenness.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a phase characteristic correction circuit which is a feature of this invention, FIG. 8 is a block diagram showing a conventional device, and FIG. 4 is a VH5
FIG. 2 is a diagram showing frequency allocation of a VTR system. In the figure, (1) is a high-pass filter, (2) is a low-pass filter, (3) is a mixing circuit, (4) is a frequency characteristic correction circuit, (5) is an amplifier circuit, and (7) is a magnetic head. , (9) is a phase characteristic correction circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A low-pass filter that passes the band of the low-pass converted color signal to be recorded, a high-pass filter that passes the band of the FM-modulated luminance signal to be recorded, and the low-pass converted color signal and FM that have passed through each of the above filters. A mixing circuit that mixes the modulated luminance signal with a modulated luminance signal, a frequency characteristic correction circuit that corrects the frequency characteristics of the mixed signal output from the mixing circuit, a phase characteristic correction circuit that corrects the phase characteristics of the mixed signal, and the frequency and phase characteristics A magnetic recording and reproducing device equipped with an amplification circuit that amplifies the corrected mixed signal and drives a magnetic head.