JPH05143906A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To enable edition without deteriorating the recording information by starting and ending the recording using a second recording head having the same gap width with the recording track when overwriting information on the recorded recording information at the time of edition in an insert edition mode. CONSTITUTION:The normal signal recording with less mechanism system error is performed by a first recording and reproduction head 10 with wider gap width than a recording track. The insert edition is performed with a second recording head 103 located at the different position from the head 10 and having almost equal or narrower gap width with the recording track without destructing the recorded signal. In the case of the edition in the insert edition mode, the information is overwritten on the recorded information and the recording is started or ended by the second recording head 103 having the same gap width with the recording track, enabling the information recording and reproduction with good S/N.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus which employs an azimuth recording system in which a guard band is not provided between tracks.

[0002]

2. Description of the Related Art A magnetic recording / reproducing apparatus adopting a helical scan method, which is a method of recording / reproducing a wide band signal such as a video signal on a magnetic tape, has already been commercialized as a VTR or DAT. Here, the head gap width error,
VT due to mounting error when the head is mounted on the drum, rotational shake of the drum, distortion of tracks on the tape, etc.
An error may occur in a mechanical system such as R.

FIG. 5 is a diagram for explaining the track arrangement of the tape when the guard bandless azimuth recording is performed. As shown in FIG. 5, with respect to the ideal recording track locus shown by the solid line, due to the mechanical system and other factors,
In reality, the recording track may be distorted and recorded.

When information is recorded by distorting the recording track as described above, the recorded signal cannot be sufficiently reproduced even if the head traces a proper track locus during reproduction. Further, when information is reproduced by using a device different from the device used for recording information, a mechanical error peculiar to the reproducing device is further added,
Since the recorded track locus cannot be tracked, the recorded signal may not be reproduced sufficiently (see the track locus shown by the broken line in FIG. 5).

In order to solve this problem, improvements were made to widen the gap width of the recording / reproducing head. By widening the gap width, it is possible to prevent an error in the head width during recording and a reduction in reproduction output during compatible reproduction.
However, the use of such a wide head has the following drawbacks. This will be described with reference to FIG.

FIG. 6 shows the relationship between tracks when insert editing is performed. The shaded tracks represent the tracks of the signal inserted by insert editing, and the other tracks represent tracks that were recorded on the tape in advance. The recording / reproducing head is designed to have a wide gap width, and at the time of recording, the next track having a different azimuth is recorded so as to be overwritten on the edge portion of the previous recorded track. In this case, since the width 301 of the recording head is wider than the track width 302, when the track 303 is recorded at the edit end point B in this figure, the recording head overwrites a part of the track 304 and Some information has been erased. For this reason, the track 304 has lost part of the information necessary for reproduction, and only image information having a reduced S / N can be obtained during reproduction.

[0007]

As described above,
In guard bandless azimuth recording, if a recording / playback head with a gap width wider than the recording track is used to prevent a reduction in playback output due to a mechanical error, the edit start point or edit end point should be around before and after editing. There was a risk of destroying the recorded signal of.

An object of the present invention is to provide a magnetic recording / reproducing apparatus capable of performing excellent editing work without destroying already recorded signals even when a recording / reproducing head having a wide gap width is used. To do.

[0009]

In order to solve the above-mentioned problems, the present invention has a gap width wider than a recording track width in a magnetic recording / reproducing apparatus, and adjacent tracks on a tape have different azimuth angles. The recording information is supplied to the first recording / reproducing head for performing recording as described above and reproducing the recorded signal, the second recording / reproducing head having a gap width equal to or smaller than the recording track width, and these two recording / reproducing heads. And means.

[0010]

In the magnetic recording / reproducing apparatus of the present invention, normal signal recording with a small mechanical system error is performed by the first recording / reproducing head having a wider gap width than the recording track. Then, the second recording head, which is installed at a position different from that of the first recording / reproducing head and has a gap width substantially equal to that of the recording track or a gap width narrower than the recording track (less than the recording track width), is used for insert editing. When performing, the insert recording is performed by the second recording head without destroying the already recorded signal.

With such a configuration, when editing is performed in the insert edit mode, the second recording head having a gap width substantially similar to the recording track when overwriting the already recorded recording information. Start recording,
Or, by ending the recording, it is possible to perform insert editing without spoiling the recorded information that has already been recorded. Therefore, compared to the case where conventional insert editing is performed only with a head with a wide gap width, It is possible to record and reproduce information having excellent S / N.

[0012]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 is a block diagram showing a main part of a recording / reproducing system of a digital VTR. The modulated digital signal is input to the input terminal 101. In normal recording / reproducing, the magnetic heads 102 and 103 are used. Recording amplifier
Reference numerals 104 and 105 are amplifiers for supplying recording currents to the recording heads 102 and 103, respectively, and are controlled by control signals 107 and 108 from a control circuit 106 to operate only during a signal recording period. Switches 109 and 110 are switches for switching between a recording mode and a reproduction mode, and are controlled by control signals 111 and 112 from the control circuit 106. The preamplifiers 113 and 114 amplify the signals read from the magnetic tape by the magnetic heads 102 and 103 during reproduction, and output the output terminals.
Output from 115 and 116. Normally, an equalizer or a digital data detection circuit is connected to this output terminal, but since it is not directly related to the present invention, its explanation is omitted.

The head 117 and the delay circuit 118 are provided for the editing function. The head 117 has the same azimuth angle as the head 103, but the head 103 has a wider gap width than the recording track, whereas the head 117 has substantially the same gap width as the recording track.

As shown in FIG. 2, the head 117 is mounted slightly behind the head 103 with respect to the rotating direction of the drum, so that the delay circuit 118 is provided only for the time difference due to the difference in the mounting position. The signal to be recorded is delayed so that the timing on the tape is the same. In Figure 2
210 is a rotating drum, and 202 is a magnetic tape.

Next, the operation at the time of insert editing will be described with reference to FIG.
Will be briefly described using. Insert edit is an edit mode in which new contents are inserted into a part of a tape recorded in advance.

If the symbols A to B are rewritten by insert editing, the recording / reproducing head 2 operates in the reproducing mode up to the track 305, and when the head 103 finishes reproducing the track 305, the head 102 tracks the track.
After the recording of 306 is started, the head 103 and the head 104 alternately record new tracks while erasing the previously recorded tracks. After the head 102 records two tracks before the editing end point B, the last track is recorded not by the head 103 but by the head 117. head
Since the gap width of 117 is almost the same as the recording track, the track is switched at the dotted line 307 and the next track 304
There is no scraping. If the track 303 is recorded by the head 103, a part of the track 304 is erased as described above, so that the signal cannot be reproduced normally due to the deterioration of the S / N when reproduced later. Will end up.

In this embodiment, an image is recorded by providing one editing head 117, but the editing head 119 can be provided at a position opposed to the head 117 by 180 degrees. This is shown in FIG.

This is a block diagram of the recording / reproducing section when two editing heads 117 and 119 are provided. Since the main part of the configuration is the same as that shown in FIG. 1, description thereof will be omitted. The difference from FIG. 1 is that the editing head 119 and the delay unit 120 are
Is provided. Editing head 119, delay unit 120
The operation of is similar to the operation of the editing head 118 and the delay unit 120, respectively. By providing multiple editing heads in this way, it is possible to shorten the time until the contact point of the tape meets the editing head when the insert editing is finished, so insert editing can be performed using the editing head. This makes it easier to perform high-quality editing work.

Further, the editing heads 117 and 119 can be used for other purposes. For example, it can be used as a special reproduction head for shuttle reproduction or the like. This will be described with reference to FIG.

This shows the trajectory of the recording / reproducing head on the tape during shuttle reproduction. Recording / playback head
During shuttle playback, 103 and 102 draw a trajectory that crosses the recorded track diagonally. At this time, since the reproduction is performed by using only a part of the recorded information, the image quality is deteriorated as compared with the normal reproduction. In this case, when the editing head added by the present invention is used for reproduction, a locus as shown in the figure is drawn.

This means that the editing head picks up information that has not been used in the conventional shuttle reproduction, and the amount of information used in the reproduction increases in this way. However, the image quality is improved. By using the editing head as described above, it is possible to perform high-quality reproduction even during shuttle reproduction.

In the above embodiment, the head 117 for editing the track recorded last at the time of insert editing is used.
However, the recording order of the heads 102 and 103 may be reversed and the first track may be recorded by the head 117. Similarly, in the embodiment having a plurality of editing heads shown in FIG. 3, the recording order can be reversed and recording can be performed using the editing head for the first track.

With this method, it is possible to prevent the recording track width at the editing start point on the tape from becoming narrow, and thereby the S / N ratio at the time of recording / reproduction being deteriorated. That is, this method can also prevent the deterioration of the screen at the start and end of the insert mode.

[0025]

As described above, in guard bandless azimuth recording, even when a recording / reproducing head having a gap width wider than the recording track width is used in order to prevent a reduction in reproduction output due to a mechanical error, the There is no risk of editing by previously deleting the track width before and after the editing start point or the editing end point, and good editing work with a good S / N ratio can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram of a recording / reproducing unit of a digital VTR of the present invention.

FIG. 2 is a diagram showing a mounting position of an editing head used in the present invention.

FIG. 3 is a diagram illustrating another embodiment of the present invention.

FIG. 4 is a diagram showing an example of utilizing an editing head.

FIG. 5 is a diagram for explaining track arrangement on a tape.

FIG. 6 is a track diagram for explaining the influence of a mechanical system error.

[Explanation of symbols]

 101 recording signal input terminal 102, 103 recording / reproducing head 104, 105 recording amplifier 106 control circuit 107, 108 recording gate signal 109, 110 recording / reproducing changeover switch 111, 112 recording / reproducing changeover switch 113, 114 preamplifier 115, 116 reproducing signal output terminal 117 Editing Head 119 Delay Circuit 201 Drum 202 Tape 301 Head Gap Width 302 Recording Track Width 303, 306 Newly Recorded Track 304, 305 Prerecorded Track 307 Track Boundary When Using Editing Head

Claims (2)

[Claims] 1. A magnetic recording / reproducing apparatus for providing a recording track oblique to the traveling direction of a magnetic tape, and recording / reproducing a signal so that adjacent recording tracks have different azimuth angles. A first recording / reproducing head having a wider gap width, a second recording head having a gap width less than the track width of the recording track, and a means for supplying a recording signal to the first and second recording heads. From the relative position between the position of the first recording / reproducing head and the position of the second recording head.
The time for supplying a recording signal to the recording / reproducing head and the second
And a means for providing a time difference between the time when the recording signal is supplied to the recording head and the magnetic recording and reproducing apparatus. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the second recording head is used for recording at the start of insert editing of the signal or at the end of insert editing of the signal.