JPH0731768B2 - Magnetic recording / reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus having a rotary magnetic head such as a helical scan type video tape recorder (hereinafter referred to as VTR), and particularly to time axis compression by the rotary magnetic head. The present invention relates to a magnetic recording / reproducing device configured to record / reproduce a reproduced audio signal.

2. Description of the Related Art As a conventional magnetic recording / reproducing apparatus, for example, Japanese Patent Laid-Open No. 59-12
No. 7203. FIG. 6 shows a plan view of a rotary drum device of this conventional magnetic recording / reproducing apparatus. Here, in the above publication, a method of mixing the luminance signal and the color signal in the video signal and recording and reproducing with one magnetic head is described, but here, the luminance signal and the color signal are recorded with different heads respectively. The Y and C separation recording method will be described. In FIG. 6, the magnetic tape 1 is wound around the rotary drum 2 and runs at a constant speed in the direction of arrow a in the drawing. The rotary drum 2 rotates at a high speed in the direction of arrow b in the drawing, and has a magnetic head 3 for luminance signal and a magnetic head 4 for color signal which have azimuth angles in opposite directions and have a height difference corresponding to one track pitch. It has. Further, heads 3'and 4'having the same specifications are provided at an angle position of 180 ° with this head respectively, and each of them records and reproduces a signal for one field. The same magnetic heads 5, 6, and 5 are provided at positions 5/3 fields ahead of the magnetic heads 3, 4, 3 ', 4'.
5'and 6'are provided on bimorph plates 7 and 7'composed of piezoelectric elements to displace the head in the track width direction. The flying erase heads 27 and 27 'erase the luminance signal and chrominance signal tracks at the same time. With the above structure, at the time of recording, the magnetic heads 3, 4, 3 ', 4'are used for the luminance signal video tracks (VY1, VY2, ...) and the color signal tracks (VC1, VC2, ...) as shown in FIG. And the audio signal of two channels (A.CH1-1, A.CH1-
2, A.CH1-3 ...) (A.CH2-1, A.CH2-2, A.CH2-3, ...
...) is recorded at the timing shown in FIG. During reproduction, the magnetic head 5, in order to match the output timings of the video signal and the audio signal, as shown in FIG.
6,5 'and 6'reproduce only the audio signal 5/3 fields ahead of the video signal. During recording, the magnetic heads 5, 6, 5 ', 6'are replaced by the magnetic heads 3, 6, 5', 6'to check the recording head for clogging and monitor the recording status. Play the recorded tracks at the same time.

Problems to be Solved by the Invention However, in the above-mentioned configuration, the magnetic heads 5, 6, 5 ′,
6'must be displaced from the audio pre-reproduction position (c in Fig. 7) to the simultaneous reproduction position (Fig. 7d).
In the figure, a displacement of 4 track pitches is required. This is the same as the maximum head displacement amount during special playback of the YC separation recording system VTR currently in practical use ± 4 track pitches (around 2x speed from still), which is always the maximum amount during simultaneous playback. A voltage must be applied to the piezoelectric element to shorten the life of the piezoelectric element. (In general, the element life is said to be inversely proportional to the product of the applied voltage and time.) The YC separation recording method is a method adopted in high-class VTRs for broadcasting and requires high sound quality. Therefore, if a longer time is required for the compression process and the reproduction process shown in FIG. 8, it is necessary to re-lead the track further before the position c in FIG. 7, which further shortens the life. Further, when applied to a high quality VTR or the like in which one field signal is divided into a plurality of tracks and recorded, the required displacement amount remarkably increases. In addition, since the valmorph 7 and 7'is a mechanism that fixes one position and uses the other twister to displace the head position, the head step tilts as the displacement increases, the contact state with the magnetic tape deteriorates, and the output during simultaneous reproduction is output. Will be lowered and sufficient monitoring will not be possible. Further, the present inventor has proposed the structure shown in Japanese Patent Laid-Open No. 61-165804 as a prior reproduction method of an audio signal. When recording, the time-axis-compressed audio signal is recorded by another head that scans backward from the video recording head, and when reproducing, both the video and audio are reproduced by the same head, thereby relatively preceding the audio signal. Simultaneous reproduction is for reproducing a video signal during an audio unrecorded period of the audio signal recording head. With this method, it is not necessary to displace the head in the track width direction, but it is necessary to provide a timing difference required for audio pre-reproduction between both heads, and an interval of several track pitches is required in the head height direction. When the magnetic tape is helically wound around the drum with such a head arrangement, the physical conditions such as the tape tension air fill amount are greatly different at both head positions, so a good contact state between the magnetic tape and both heads is secured. It was difficult to do so.

SUMMARY OF THE INVENTION In view of the above points, an object of the present invention is to provide a novel magnetic recording / reproducing apparatus capable of pre-reproducing an audio signal recorded by time axis compression without displacement of the magnetic head and with a small height difference.

The present invention comprises a first magnetic head for recording a video signal, and a second magnetic head for recording a time-axis-compressed audio signal at a position following the first magnetic head on a drum. In the magnetic recording / reproducing apparatus, the video signal is reproduced by the second magnetic head and the audio signal is preliminarily reproduced by the first magnetic head during reproduction.

Function The present invention records a time-axis-compressed audio signal at a position preceding a predetermined amount (timing difference between the first and second magnetic heads) in the longitudinal direction of the magnetic tape during recording.
At the time of reproduction, since the audio signal can be reproduced at a timing further ahead by reproducing both signals by the heads opposite to those at the time of recording, both heads are not displaced, and a small head mounting height difference is ensured. Audio signal precedent reproduction can be performed.

Example 1 FIGS. 1 (a) and 1 (b) show a plan view of a rotating drum of a magnetic recording / reproducing apparatus in an example of the present invention and a configuration diagram showing a height relationship of a magnetic head provided on this drum. is there. In FIG. 1 (a), 8 is a magnetic tape, and an arrow e
Drive in the direction. The magnetic tape 8 is helically wound and guided around the outer circumference of the drum 9 which rotates in the direction of arrow f. A video signal luminance video head 10 and a color signal video head 11 are fixed to the drum 9, and a set of similar heads 10 ', 1 are provided at positions opposite to the fixed positions.
1'is fixed. In addition, the same magnetic heads 12 and 13 are placed at a position 60 ° behind this head with respect to the drum rotation method.
Is provided on a bi-morse plate 14 composed of two piezoelectric elements and is displaceable in the height direction. A set of similar units 12 ', 13', 14 'is also provided at the position opposite to this. The magnetic heads 12 and 13 are mounted lower than the magnetic heads 10 and 11 by two track pitches as shown in FIG. 1B, and the magnetic heads 12 'and 13' facing each other are the same. Next, the erasing heads 15 and 15 'are the magnetic heads 1
It is provided at a position advanced by 60 ° in the drum rotation direction from 0 and 11, and is configured to erase both tracks (for luminance signal and color signal) at the same time. The bimorphs 14 and 14 'are connected to a tracking control circuit and a bimorph drive circuit, respectively, and each video head is connected to each circuit as shown in FIG. First, at the time of recording, the magnetic heads 10, 11, 10 ', 11' are connected to the video signal recording circuit via the changeover switch 16 as shown in FIG.
12 'and 13' are connected to a video signal simultaneous reproducing circuit or an audio signal recording circuit via changeover switches 17 and 18, respectively. When reproducing, as shown in FIG. 2B, the magnetic head
10,11,10 ', 11' are audio reproducing circuits, magnetic head 1
2, 13, 12 'and 13' are connected to a video signal reproducing circuit.

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

First of all, from the time of recording, each circuit is connected to the magnetic head as shown in FIG.
The sets of magnetic heads are alternately switched for each field to record a signal on the magnetic tape. The recording tracks by the magnetic heads 10, 11 and 12, 13 at this time are shown in FIG. 3, where the magnetic heads 10, 11 form video signal tracks 19, 20 and the magnetic heads 12, 13 form the audio signal track 21 (CH1 ), 22 (CH
2) to form. The timing of the video signal and the audio signal recorded on the tape at this time will be described with reference to FIG.
The magnetic heads 10 and 11 record the video signal A on the tracks 19 and 20, and the magnetic heads 12 and 13 following the magnetic heads 10 and 11 record the audio compression signal during the shaded portion in FIG. 4 at the recording signal position. To do. At this time, when the audio compressed signal is recorded by the magnetic heads 10 and 11 which record the video signal as in the conventional case, the fourth
Although the position is described as the compressed signal in the figure, the signal is recorded at the preceding position on the magnetic tape 8 on the contrary because the magnetic heads 12 and 13 are displaced by the mounting height of the magnetic head in the following direction. To be done. And in this embodiment, the timing difference is
Since it is set to 4/3 fields, it means that the audio signal was prerecorded in 4/3 fields at the time of recording. Next, the time of reproduction will be described. At the time of reproduction, as shown in FIG. 2B, each circuit is connected to a magnetic head, and basically a head recording a video signal reproduces an audio signal and a head recording an audio signal reproduces a video signal. ing. Therefore, the magnetic heads 12 and 13 reproduce the video tracks 23 and 24 shown in FIG.
Since the audio tracks 25 and 26 are played back, the audio signal during playback is 4/3 more from the time of recording as shown in FIG.
This means that field pre-reproduction is performed, and in total, it is possible to output in the same phase as the video signal pre-reproduced for 8/3 fields. Next, simultaneous reproduction at the time of recording will be described.
Simultaneous playback is magnetic head for audio signal recording 12,13,1
The operation is performed only during the period in which the audio signal is not recorded at 2'and 13 ', and both operations are switched by the changeover switch 18 in FIG. FIG. 5 shows this operation, and the video tracks 23 and 24 of FIG. 3 are reproduced and monitored during the reproduction mode period. Here, the reason why the recording mode period is raised earlier by S by the audio recording period is to sufficiently stabilize the circuit of the recording system. Further, in the present invention, the audio signal recording heads 12, 13, 12 ', 13' are connected to the bimorph plate 1
Since it is attached to 4, 14 ', it is common to control the tracking position during recording. Next, the operation will be described.
First, during the simultaneous reproduction period, a signal from the piezoelectric element control signal A shown in FIG. 5 is supplied to the bimorphs 14 and 14 'to displace the magnetic heads 12, 13, 12' and 13 'in the track width direction by both predetermined directions. At the same time, the level L of the head reproduction output during the T period is checked, and tracking control during recording is performed by supplying a control signal at the maximum level position during the recording mode period. Here, the level check period is set to the T period of reproduction output because contact failure occurs at the contact start and end positions of the head and accurate check cannot be performed. Therefore, the piezoelectric element control signal may be displaced only during the T period as shown by B. In addition, if the above control is performed during the entire recording operation period of the device, good synchronous reproduction output cannot be obtained, so only one field at the start of recording (actually two fields because it is necessary to perform recording until the head at the opposite position) is executed. After that, the control signal is held. Then, when continuously recording for a long time, the above check may be repeatedly performed at regular intervals, and if it changes, it may be corrected. Therefore, an audio track can be faithfully formed on the extension of the video track recorded by the fixed head. Further, by further adding the above-mentioned audio pre-reproduction operation, the total necessary pre-reproduction timing can be calculated from the time (compression processing and reproduction processing in FIG. 4) required to perform various signal processing of the audio signal (this (8/3 field in the embodiment) The mounting phase difference between the video signal recording magnetic head and the audio signal recording magnetic head is basically set to 1/2 of the total preceding amount (4/3 field in this embodiment). It suffices to do this by setting the relative mounting angle and the relative mounting height difference between both heads shown in FIG. Although the value can theoretically be set arbitrarily, in practice, it should be largely restricted from the aspect of the head arrangement and the settable range should be limited. In addition, at the time of special reproduction, the bimorph board as before
This can be done by displacing the magnetic heads 12, 13, 12 ', 13' with 14,14 '.

As described above, according to the present invention, the first magnetic head for recording the video signal and the second magnetic head for recording the time-axis-compressed audio signal at the position following the first magnetic head are rotated. Since it is arranged on the drum so that the video signal is reproduced by the second magnetic head and the audio signal is reproduced by the first magnetic head at the peak time, the head is not displaced, and the number is smaller than the conventional one (about 1 / 2) It is possible to perform audio pre-reproduction and video signal simultaneous reproduction at the time of recording by the phase difference of the head mounting. This is a bimorph board
It is said that the piezoelectric elements that make up 14,14 'can have a long life and that a good contact state between the magnetic head and magnetic tape during recording / reproduction (except for special reproduction) can be easily ensured and can be stabilized for a long time. effective. Further, since the tracking of the movable magnetic head at the time of recording the audio signal is controlled by the optimum tracking signal at the time of simultaneous reproduction, the pattern accuracy of the recording track can be improved and a good reproduced audio signal can be obtained. In addition, by optimizing the tracking during simultaneous playback described above so that it repeats at the start of recording and at regular intervals thereafter, it is possible to secure a highly accurate tracking state for a long time without affecting the playback output during simultaneous playback. Its practical effect is great.

[Brief description of drawings]

1A and 1B are a plan view of a rotary drum and a head configuration diagram of a magnetic recording / reproducing apparatus according to an embodiment of the present invention, and FIGS.
B is a block diagram showing the recording and connection with each circuit at the time of life in the same embodiment, FIG. 3 is a plan view showing a signal track recorded on the magnetic tape of the same embodiment, and FIG. A timing chart showing the passage of time during recording and reproduction of an example video and audio signal, FIG. 5 is a detailed view of various signals relating to tracking control, and FIG. 6 is a plan view of a rotary drum of a conventional magnetic recording / reproducing apparatus. FIG. 7 is a plan view showing a tape pattern recorded by a conventional device, and FIG. 8 is a timing chart showing a time lapse of conventional video and audio signals. 9 ... Rotating drum, 10,11,10 ', 11' ... First magnetic head, 12,13,12 ', 13' ... Second magnetic head, 14,14 '
...... Bimorph board.

Claims (4)

[Claims] 1. A first magnetic head for recording a video signal on a magnetic tape, and a second magnetic head for recording a time-axis-compressed audio signal at a position following the first magnetic head. Simultaneous reproduction of a video signal is performed in a period in which the second magnetic head does not record an audio signal, and at the time of reproduction, the second magnetic head reproduces the video signal and the first magnetic head precedes the reproduction of the audio signal. And a magnetic recording / reproducing apparatus. 2. A mounting phase difference between the first magnetic head and the second magnetic head is set to about 1/2 of a preceding reproduction amount required for timing alignment of audio signals. 2. The magnetic return reproduction device according to item 1. 3. A second magnetic head is provided on a member that can be displaced in the track width direction, and tracking control means for the second magnetic head is provided to perform tracking control during an audio signal recording period with a tracking signal during a simultaneous reproduction period. The magnetic recording / reproducing apparatus according to claim 1, wherein the magnetic recording / reproducing apparatus is configured as described above. 4. The tracking optimization control is repeatedly performed at the start of recording and at regular intervals thereafter, and the control signal immediately before is held during each control operation. 3. A magnetic recording / reproducing apparatus according to item 3.