JPS62185497A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To remove a skew produced during a switching by changing the delay time of a variable delay line and to stably reproduce a chrominance signal during the switching by passing the outputs of the variable delay line through another chrominance synchronizing circuit (APC) by respectively passing the reproducing RF signal of a main rotary head and the reproducing RF signal of an auxiliary rotary head through another variable delay line. CONSTITUTION:The inputs X, Y of a switch 18 are directly inputted to two skew correction circuits 24a, 24b. A chrominance signal processing circuit 36 has the two APC circuits 36a, 36b, and the output of the skew correction circuit 24a is inputted to the APC (1) 36a and the output of the skew correction circuit 24b is inputted to the APC (2) 36b and respectively synchronized in chrominance. The skew correction and the chrominance synchronization thereafter are performed by the signal (waveform F) formed by a timing circuit 37 so as to operate the synchronization timing before several Hs (the time when the chrominance synchronization is stabilized) of a head switching signal 23. The chrominance signal synchronized in chrominance is switched by a switch 38 according to the head switching signal 23 and a luminance signal is switched by a switch 39 in the same timing as the switching signal 23.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic recording and reproducing apparatus capable of special (variable speed) reproduction, such as a rotating head type azimuth recording type video tape recorder.

(Prior Art) In a video signal recording and reproducing device using magnetic tape such as a video tape recorder, as a means of realizing high-speed playback or reverse high-speed playback without noise bars, the recess of the playback head output of the main rotary head is The proposed method is to embed the playback head output, but this causes visual problems as screen distortion and color synchronization are disrupted due to skew at the switching timing on the screen.

The conventional technology will be explained in more detail using the drawings.

FIG. 3 is a diagram showing the main part of a conventional rotary disk 1, and FIG. 4 shows an example of a track pattern of a magnetic tape recorded azimuthally.

In FIG. 3, Ml is a main rotating head with an azimuth angle of +6'', and S is an auxiliary rotating head with an azimuth angle of -6''. M2 is another main rotating head with an azimuth angle of -6″, and S2 is another auxiliary rotating head with an azimuth angle of +6°. Main rotating head M2
and M2 are 180° apart from each other. Auxiliary rotating heads S2 and 82 are also 180° apart from each other. The main rotating head and the auxiliary rotating head are separated by a distance corresponding to, for example, two horizontal signal periods of the video signal, and are placed on the same rotating plane of the rotating disk (or drum) 1, as shown in FIG. installed.

A schematic track pattern of a magnetic tape is shown in FIG. 4. In FIG. 4, tracks 2, 4, 6°8.10 and 12 are recorded with a rotary head having an azimuth angle of +6", and tracks 3, 5,7,9°11 and 13 are
The diagonal line in each track of 6 in FIG. 4, which is a track recorded by a rotary head having an azimuth angle of -6@, indicates the horizontal synchronizing signal recording position, and the inclination angle indicates the azimuth angle.

Furthermore, a shift in diagonal lines in adjacent tracks indicates that the horizontal synchronization signal during recording is shifted due to cylinder jitter.

As an example of high-speed playback, track 14 in FIG.
An example of 9x speed playback is shown below.

At this time, the main rotating head M□ has an azimuth angle of +6°, so the head output (, f
Get the f number. Further, since the auxiliary rotary head S has an azimuth angle of -66, a head output signal as shown in FIG. 5(B) is obtained. During high-speed reproduction as shown in FIG. 5(A), several noise bars (portions where the head output signal is zero) occur within the field. This is because the output of the reproduced RF signal of the main rotary head M1 decreases, and by replacing this with the reproduced output signal of the auxiliary rotary head S as shown in FIG. 5 (II), C), it can be removed. However, as mentioned above, when switching between the main rotary head reproduction signal and the auxiliary rotary head reproduction signal, the deviation of the recorded horizontal synchronization signal causes a change in the interval of the horizontal synchronization signal to be reproduced, resulting in a skew at the switching point. As this occurs, color synchronization becomes unstable and noise becomes noticeable.

Main rotating head M, , M, and auxiliary rotating head S1゜Sl
For example, in the case of 9x speed, the switching is performed as follows. In Fig. 6, the switches 15 and 16 are
When the head switch signal like D) is at H level, it goes to the X side, for example, and when it is at L level, it goes to the X side.

Connected to the Y side. Now, when the head switch signal 17 is set to H level, reproduction outputs as shown in FIGS. 5(A) and (+3), for example, are obtained from the main rotary head M and the auxiliary rotary head S1, respectively. Similarly, head switch signal 1
7 is at the L level, signals as shown in FIGS. 19 to 22 in FIG. 6 are head amplifiers.

The movable piece of the switch 18 is connected to the Y side when the signal applied to the terminal 23 is at the H level, and to the X side when the signal is at the L level. If the switching is performed by applying the auxiliary rotary head switching signal, the output terminal of the switch 18 will be turned on.

An RF multiplied signal shown in FIG. 5(C) is obtained. This is skew-corrected through the skew auxiliary circuit 24 in Fig. 6, and then separated into luminance signal processing and color signal processing, and the luminance signal and APC (color synchronization circuit, auto phase controller) are used to transport 3.58M1lz. After converting to a color signal, the luminance signal and carrier color signal are mixed and output as a video output.

Next, a skew correction method will be explained.

First, the amount of skew is detected using a closed loop circuit consisting of a phase comparator, a low-pass filter, and a voltage-controlled oscillator (hereinafter abbreviated as CO) as follows. The output obtained from the video signal demodulation circuit 25 in FIG. The phase of the horizontal synchronization signal input to the phase comparator is compared with the output of a VCO (voltage controlled oscillator) 28.

The phase difference becomes an error signal voltage and is applied to the output terminal of the phase comparator. This output passes through a low-pass filter 29 and controls the oscillation frequency of VC028.

The error signal voltage obtained in this way is input to the sample and hold circuit 30, and the timing signal generation circuit 31
The control voltage of the VCO 32 is obtained by the sample pulse output from the VCO 32.

The control voltage obtained as described above is applied to the clock driver 34 that drives the CCD (charge coupled device) 33, and a voltage proportional to the skew amount is used to
Skew correction is performed by continuously varying the clock of the CCD 33.

As described above, the skew-corrected RF multiplied signal is separated into a luminance signal and a chrominance signal as shown in FIG. After converting into a 3.58 MHz carrier color signal through a color signal processing circuit 36 connected to an APC loop, the luminance signal and color signal are mixed and output.

However, the configuration described in the conventional example has the drawback that sufficient color synchronization cannot be achieved, resulting in noise on the screen and noticeable discontinuity. In the conventional example.

As shown in Fig. 9, after head switching (E), the output signals of Fig. 5 (A) and (B) are demodulated (Fig. 9 (A)', (B)''), and the color remains unchanged. Since it takes several H (horizontal synchronization frequency) for the signal processing circuit 36 to stabilize, color noise due to instability of color synchronization becomes noticeable after switching, as shown in the shaded areas in FIG. 9 (A)' and (B)'', and the screen Above, a noise bar appears as a discontinuous line at the timing of head switching.

(Problems to be Solved by the Invention) The present invention provides a magnetic recording medium that can reproduce brown signals without generating noise bars or skews, not only in still playback and slow motion playback, but also in high-speed playback and reverse high-speed playback. The purpose of this invention is to provide a recording/playback device.

(Means for solving the problem) The present invention uses an auxiliary rotary head installed close to the main rotary head, and switches the output RF multiplied signal level of the main rotary head to the output RF multiplied signal of the auxiliary rotary head. At the same time, the reproduced RF signal of the main rotary head and the reproduced RF signal of the auxiliary rotary head are passed through separate variable delay lines.

The skew that occurs during switching is removed by changing the delay time of the variable delay line, and the output of the variable delay line is passed through separate color synchronization circuits (APCs) to stabilize color signal reproduction during switching. It is designed so that it can be carried out.

(Function) As described above, the reproduction outputs of the main rotary head and the auxiliary rotary head are each controlled by a variable delay line (COD) in the RF band.
), compared to conventional baseband (FM demodulated video signal) skew correction, DC level fluctuations, DC gain fluctuations, linearity, etc. when switching variable delay line clocks are reduced. The problem disappears and subsequent color signal synchronization becomes stable. Also, it has two systems each for skew correction circuit and color synchronization circuit.

Further stable color signal reproduction can be obtained.

(Embodiment) FIG. 1 shows an embodiment of the present invention, which solves the drawbacks of the conventional example. The inputs X and Y of the switch 18 in FIG. 6 are directly connected to the two skew correction circuits 24a and 24.
The 1-signal processing circuit 36 input to B has two APC circuits 36a and 36b, the output of the skew correction circuit 24a is input to the APC 36a, the output of the skew correction circuit 24b is input to the APC 36b, Each color is synchronized. The synchronization timing is head switching signal 2.
A signal created by the timing circuit 37 to operate before the number H of 3 (the time when color synchronization is stabilized)
F)) with skew correction and subsequent color synchronization (APC
) The synchronized color signal is switched by a switch 38 according to the head switching signal 23, and the luminance signal is switched by a switching 39 at the same timing as the switching signal 23, and then demodulated by a luminance signal processing circuit 35. After that, it is combined with a color-synchronized stable color signal which is the output of the switch 38, and is output.

FIG. 2 is a timing diagram of the configuration described in one embodiment of the present invention, in which skew correction and APC are performed at the timing of the output (F) of the timing circuit 37.

The timing time is head switching (waveform (r
i)) The time when the A P Cl path stabilizes in front of each of the two APC circuits 36a (FIG. 2, shaded area).

Head switching signal 2 after 36b is sufficiently stable.
3. Therefore, as shown in FIG. 2, when the outputs of the APCs 36a and 36b are combined, the color signal noise is not noticeable and the discontinuity caused by head switching on the screen is eliminated.

(Effects of the Invention) As is clear from the above description, the present invention provides a magnetic recording and reproducing device in which noise bars and skew do not occur not only in still playback and slow motion playback, but also in high speed playback and high speed reverse playback. 6 Furthermore, by using a configuration in which skew correction is performed through COD in the RF band, the C
DC level fluctuation during OD tarot switching, D
Problems such as C gain fluctuations and linearity are eliminated, and subsequent color signal synchronization becomes stable. Further, the present invention has two systems each of a skew correction circuit and a color synchronization circuit (APC) having the above characteristics.

Furthermore, stable color signal reproduction can be obtained, and noise-shifted images can be realized during special reproduction.

The present invention has two color synchronization circuits, each of which is synchronized in advance so that color synchronization can be reproduced stably before head switching, and in order to synthesize the synchronized output signals according to the timing of head switching. A stable reproduced color signal can be obtained.

[Brief explanation of drawings]

FIG. 1 is a signal processing block diagram showing an embodiment of the present invention;
FIG. 2 is the time chart 1-. FIG. 3 is a diagram showing an example of a cylinder section of a magnetic recording/reproducing device, FIG. 4 is a track pattern diagram of a magnetic tape recorded azimuthally, and FIG.
The figure shows a time chart of the signals in Figure 3 above, Figure 6 is a block diagram showing a conventional head switch, Figure 7 is a block diagram of a skew correction circuit, Figure 8 is a signal processing block diagram of a conventional example, and Figure 8 is a block diagram of a conventional head switch. Figure 9 is the time chart. M,,M,...Main rotating head, Sl,S,...Auxiliary rotating head, 24...Skew correction circuit, 36...
- Color signal processing circuit, 36a, 36b... Color signal synchronization circuit (APC). Patent applicant Matsushita Electric Industrial Co., Ltd. Figure 1 Figure 2 Figure 5 Figure 24 Individual - Luxury

Claims (1)

[Scope of Claims] First and second main rotating heads having different azimuth angles, and having an azimuth angle that is the same as that of another main rotating head that is installed close to the main rotating head and is separated by approximately 180°. When the magnetic tape is run at a running speed different from the tape running speed during recording, the level of the reproduced RF signal of the main rotating head is reduced in units of horizontal synchronization periods, A switch means for replacing the reproduction RF signal of the auxiliary rotary head with a reproduction RF signal of the main rotary head and a reproduction RF signal of the auxiliary rotary head are respectively passed through a variable delay line, and the skew generated when switching the switch means is replaced by the reproduction RF signal of the auxiliary rotary head. skew correction means for correcting by changing the delay time of a variable delay line; a color signal synchronization circuit for synchronizing color signals in a signal after skew correction by the skew correction means; A magnetic recording and reproducing device comprising: , a combining means for obtaining a safe reproduced color signal by combining;