JPS61165805A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate the time difference produced between the video and audio signals in a reproduction mode and to attain a natural reproduction state, by providing a pair of rotary magnetic heads to the bimorph plates which has a displacement toward the track width. CONSTITUTION:A rotary drum 8 contains a pair of magnetic heads 9A and 9B having azimuth angles adverse to each other which can have the displacement toward the rotary axis of the drum 8 by means of bimorph plates 10A and 10B consisting of piezoelectric elements. The video signals SV supplied to an input terminal 13 form tracks in a video signal recording area by the heads 9A and 9B. While the audio signals SAC underwent the compression of time bases form the audio tracks in an audio signal recording area. In a reproduction mode those video and audio signals are reproduced by a head which recorded a video track TV1. At the same time, the magnetic head is displaced in a fixed head recording area for reproduction of the audio signal preceding by two fields. Thus the time difference can be eliminated between the video and audio signals by delivering both signals concurrently with a reproduction video signal after the processes including the correction of errors, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording/reproducing device having a rotating magnetic head such as a helical scan video tape recorder (hereinafter referred to as VTR), and particularly relates to a magnetic recording/reproducing device having a rotating magnetic head, such as a helical scan video tape recorder (hereinafter referred to as VTR), and in particular, to a magnetic recording/reproducing device having a rotating magnetic head. The present invention relates to a magnetic recording and reproducing device configured to record and reproduce signals.

BACKGROUND OF THE INVENTION Conventional magnetic recording and reproducing devices include, for example, Japanese Patent Application Laid-open No. 1983-
It is shown in Japanese Patent No. 127203.

FIG. 9 shows a plan view of the rotating drum device of this conventional magnetic recording/reproducing device. Although the above-mentioned publication describes a configuration in which the magnetic heads do not have an azimuth angle, a configuration using magnetic heads having azimuth angles in opposite directions will be described here. In FIG. 9, the magnetic tape 1 is wound around a rotating drum 2 and runs at a constant speed in the direction of arrow a in the figure. The rotating drum 2 rotates at high speed in the direction indicated by the arrow in the figure, and has a pair of recording and reproducing magnetic heads 3A and 3B having azimuth angles in opposite directions, and a pair of reproducing magnetic heads 4A and 4B.
are arranged at 180 degree intervals. The pair of reproduction-only heads 4A and 4B each have a bimorph plate 5A composed of an electromechanical transducer, such as a piezoelectric element, in order to perform tracking control during variable-speed reproduction.
, 5B, and is configured so that the rotational height position can be displaced and controlled. In addition, read-only magnetic heads 4A, 4
Head B is arranged to record a signal at a position 2.5 fields ahead of the recording/reproducing magnetic heads 3A and 3B. With the above configuration, when recording, first, as shown in FIG.・・・
...and 6B1. with 3B again. eB2... At this time, the video signal is recorded in real time with the input signal, and the audio signal is compressed on the time axis for one field period as shown in Fig. 11, and is recorded after the video signal. Record with the head that recorded the video signal. During reproduction, the video system reproduces the video track TV using the recording/reproducing magnetic heads 3A and 3B, and the audio system uses the reproduction-only magnetic head 4A shown in FIG. 9.

Audio track TA recorded with time axis compression in 4B
The data is reproduced at a phase 2.5 fields ahead of that at the time of recording, then subjected to signal processing such as error correction, and output at the same phase as at the time of recording. Therefore, there is no time difference between the video and audio signals during playback, and a natural playback state can be obtained. Also, during variable speed reproduction, the bimorph plates 5A, 5 are arranged so that the reproduction-only magnetic heads 4A, 4B shown in FIG. 9 follow the recording track.
B) Displace and control the rack width direction to reproduce a complete video signal.

Problems to be Solved by the Invention However, with the above configuration, two sets of magnetic heads must be provided on the rotating drum 2, which complicates the configuration of the drum unit, increases cost, and increases the size and weight of the device. do. In addition, since the video signal is not reproduced by a magnetic head provided in a bimorph, there is a problem in that, in compatible reproduction using different decks during recording and reproduction, output decreases due to trunk bending, resulting in deterioration of image quality.

In view of this, the present invention provides a novel magnetic recording and reproducing system that eliminates the time difference between video and audio playback and provides a natural playback state using a pair of rotating magnetic heads provided on a bimorph that is displaced in the trunk width direction. The purpose is to provide equipment.

Means for Solving the Problems The present invention provides a rotating magnetic head for dividing and recording a video signal and a time-axis compressed audio signal on both sides of a magnetic tape diagonally across a fixed head recording area; Displacement means for displacing in the track width direction, and a fixed magnetic head for recording and reproducing signals in the fixed head recording area; This is a magnetic recording/reproducing device configured to cause displacement in the direction.

A pair of rotating magnetic heads that are displaceable in the track width direction are moved in the track width direction in a fixed head recording area between the video and audio tracks to compress the time axis and record audio. By reproducing the signal in advance of the video signal, the pair of magnetic heads can align the timing of the video signal and audio signal during reproduction.

Embodiment FIG. 1 is a plan view showing the structure of a magnetic head of a magnetic recording/reproducing apparatus in an embodiment of the present invention. In FIG. 1, a magnetic tape 7 is helically wound around a rotating drum 8 rotating at high speed in the direction of arrow C, and runs at a constant speed in the direction of arrow d. Further, the rotating drum 8 is provided with a pair of magnetic heads 9A, 9B having azimuth angles in opposite directions, which can be displaced in the direction of the rotation axis by bimorph plates 1oA, 10B made of piezoelectric elements. The bimorph plates 1 oA and 1 oB are respectively displaced according to voltages applied from the bimorph drive circuit 11. A fixed magnetic head 12 is still provided at the tape exit of the rotating drum 8, and records and reproduces cue signals such as control signals, linear audio signals, and time codes in the longitudinal direction of the tape. FIG. 2 shows the tape pattern recorded by the above device. TV3.
TV6. TA1. TA3. TA5 with 9B T■2. TV
4. TA2. Record TA4. Here, the fixed head recording area is provided between the video track and the audio track, and the reason for this will be explained later. Further, FIG. 3 shows a circuit system during recording of the embodiment, in which a first input terminal 13 is supplied with a video signal Sv, and a second input terminal 14 is supplied with an audio signal SA. The video signal Sv is supplied to the video modulation circuit 16 and then selectively supplied to the rotating magnetic heads sA and sB via the head switching circuit 16.

Furthermore, the audio signal SA is transmitted to the analog-to-digital conversion circuit 1.
The data is digitized at a and supplied to the time axis compression circuit 18. The compression circuit compresses 1% of the audio signal for one field period.
It is configured to compress time in the field. The audio signal SAC compressed as described above is supplied to the audio modulation circuit 19 and then selectively supplied to the rotary magnetic heads 9A and 9B via the signal selection circuit 20.

FIG. 4 shows a circuit system during reproduction in this embodiment, in which the signals reproduced by the rotating magnetic heads 9A and 9B are amplified by dedicated head amplifiers 21 and 22, respectively, and then sent to reproduction signal switching circuits 23 and 24. The video signal is sent to the video demodulation circuit 2 via
5. The audio signal is then supplied from the audio demodulation circuit 26 to the time axis expansion circuit 27 and restored to the original one.
After being expanded into the field, digital-to-analog conversion circuit 2
The video signal is converted into an analog signal at 8 and output from an output terminal 29, and the video signal is output from an output terminal 30.

Further, the bimorph plates 1oA and 1oB shown in FIG. 1 are controlled to hold the magnetic head at a predetermined height position during recording, and the structure thereof will be described below. First, both bimorph plates 10A are commanded to record.

After applying an AC voltage whose level decreases over time to 10B to remove the displacement due to hysteresis and return the head height to the reference value, recording starts.
As shown in the figure, a low frequency pilot signal P1 is first inserted before the front overlap area of the video track Tv1.
Record with head 9A in the figure and record in the same way thereafter.
Then, when the head 9B scans the track Tv3, the leakage magnetic flux of the pilot P1 is reproduced during the reproduction period to obtain the first detection signal, and when the head 9A scans the track Tv3, the leakage magnetic flux of the pilot P2 is similarly obtained. is reproduced to obtain a second detection signal, and the levels of the two detection signals are compared. If they are different, it means that there is a height difference between the two heads. After that, the same detection, comparison, and correction are repeated to keep both heads at the reference height and record video and audio signals.

During playback, the bimorph is controlled as shown in FIG. First, video signal T■1. During the period of reproducing Tv2..., the magnetic head is set at the recording height, and when reproducing the audio signal 'rA1t TA2..., the audio signal that precedes by two fields is played back. When applying the voltage
Audio signal TA1. The region TA2... is configured to be stable at a displacement Y of two fields. In this way, from the viewpoint of head responsiveness, it is necessary to have a sufficient gap between the video and audio tracks to reduce the responsiveness, and the present invention is configured to record a fixed head signal in this area. be.

Also, during playback, tracking is controlled by making the magnetic head follow the curve of the track for both video and audio tracks.As shown in Figure 7, the configuration is as shown in Figure 7.During playback, AC voltage is applied to the bimorph for both video and audio tracks, and the magnetic head is tracked. It is configured to automatically determine and follow the direction and amount of bending from the level of the playback output and the amount of head displacement in the width direction.

The operation of the magnetic recording/reproducing apparatus of this embodiment configured as described above will be explained below.

The video signal Sv input to the input terminal 13 forms tracks in the video signal recording area by the magnetic heads 9A and 9B as shown in FIG. On the other hand, the time axis compressed audio signal S
AC forms audio tracks in the audio signal recording area. To explain this state using the timing chart of FIG. 8, the video signal Sv1 of one field period forms the track TV1 in real time, but the audio signal SA
1 is compressed into a signal SAC of % field within a viewing field period to form TAl. At the time of playback, the video track TV is still played back by the recorded head, and the magnetic head is displaced as shown in FIG. 6 in the fixed head recording area shown in FIG. 2 to play back the audio signal of two fields before. In Figure 8, the signal at TA7 and REC position is
Since the signal is played back at the Al and RB positions, the time lag between the video and audio signals can be prevented by outputting the signal at the same time as the playback video signal P-BS1 after performing processing such as error correction.

Further, during the above-mentioned reproduction, the magnetic head is moved in the track width direction as shown in FIG. 7, so that the track tune 9 and C can be followed during compatible reproduction, and a good output can be obtained. Also, during variable speed playback, the pair of magnetic heads may be displaced so as to accurately trace the recorded video track.

In this embodiment, the magnetic head is displaced during reproduction, but conversely, it may be possible to record two fields earlier during recording and to reproduce continuously during reproduction.

Furthermore, although a method using pyro-signals has been described for head height detection control during recording, the height position of the magnetic head or bimorph may also be directly detected and controlled by non-contact means such as a phototransistor Hall element.

As described in detail, according to the present invention, a pair of rotary magnetic heads displaceable in the track width direction are used in a fixed head recording area provided between a video track and an audio track. By configuring the audio signal to be displaced in the direction and reproduced with time axis compression before the video signal, it is possible to eliminate the time difference between the image and the sound and achieve a natural reproduction state with a simple configuration.

In addition, by simplifying the configuration, the device can be made smaller.
Effective in reducing weight and cost.

In addition, by configuring the magnetic head that plays both video and audio tracks to follow track bending during compatible playback, good playback output is obtained over the entire length of the track, and image quality is achieved.

The sound quality is improved and its practical effects are great.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a rotating drum of a magnetic recording/reproducing device according to an embodiment of the present invention, Fig. 2 is a diagram of a tape pattern recorded by the same embodiment, and Fig. 3 is a circuit system during recording of the same embodiment. FIG. 4 is a block diagram showing the circuit system during reproduction of the same embodiment, FIG. 5 is an explanatory diagram of the head height position control method during recording of the same embodiment, and FIG. 6 is the same. The bimorph drive voltage waveform diagram of the embodiment, FIG. 7 is the bimorph applied voltage waveform diagram when trunk bending is detected in the same embodiment, and FIG. 8 is the recording/playback of video and audio signals, signal processing time, etc. of the same embodiment. 9 is a plan view of a rotating drum of a conventional magnetic recording/reproducing device, FIG. 10 is a tape pattern diagram recorded with a conventional σ device, and FIG. 11 is a diagram showing the time relationship between conventional video and audio signals. FIG. 9A, 9B... Rotating magnetic head, 1oA, 10
B...Bimorph, 11...Bimorph drive circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person
1. Figure 2.) Let's work together! Figure 3. Figure 5. Figure 7. Figure 9. Figure 101! Nidasu standing slap-2

Claims (1)

[Claims] a rotating magnetic head for dividing and recording time-axis compressed audio and video signals on both sides of a magnetic tape diagonally across a fixed head recording area; and means for displacing the rotating magnetic head in the track width direction; Equipped with a fixed magnetic head that records and reproduces signals in the fixed head recording area,
A magnetic recording/reproducing apparatus characterized in that the rotating magnetic head is configured to be displaced in the track width direction during a period when the rotating magnetic head scans the fixed head recording area.