JPH09231532A - Digital information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out the first long-time recording increasing the compression rate of video signal, the second long-time recording narrowing a track pitch and the third long-time recording using both first and second long-time recordings in a digital information recording/reproducing device. SOLUTION: Other than magnetic heads A10a, B10b adjacently arranged and having different azimuth angles and a magnetic head C10c arranged on the opposite position of the magnetic heads A, B and having the same azimuth angle as the magnetic head B, a magnetic head D10d located on the opposite side of the magnetic head B while interposing the magnetic head A and having the same azimuth angle as the magnetic head A and an effective head width narrower than the other heads is provided on the peripheral side of a rotating drum and the magnetic head D is used instead of the magnetic head A only when the long-time recording narrowing the track pitch is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital information recording / reproducing apparatus for recording and reproducing digital information such as digitized video signals and audio signals on a magnetic tape by a helical scan type magnetic recording / reproducing apparatus. The present invention relates to a digital information recording / reproducing apparatus which is useful when recording for a long time by changing a track pitch.

[0002]

2. Description of the Related Art In recent years, a digital VTR has been proposed which records a digitized video signal on a magnetic tape while reducing the amount of recorded information by compression encoding using DCT or the like. A method has also been proposed in which the compression rate is further doubled to realize double the long-time recording without narrowing the track pitch unlike the conventional VHS (registered trademark) or 8 mm VTR.

As a method for realizing such a long time recording, as disclosed in Japanese Patent Laid-Open No. 6-195614, magnetic heads A and B having double azimuth and a position opposite to the double azimuth head. When the video signal is compressed and recorded at a normal compression rate using the arranged magnetic head C, the magnetic head A and the magnetic head C are alternately switched and recorded, and the video signal is compressed and recorded at a double compression rate. In this case, a method is proposed in which the magnetic head A and the magnetic head B are alternately switched and recording is performed to support two modes.

[0004]

A major reason for increasing the compression rate without narrowing the track pitch and supporting long-time recording is VHS which is conventional analog recording and 8 mm.
In the case of VTR, deterioration of the C / N of the reproduced signal due to the narrowing of the track pitch directly leads to deterioration of the image quality of the reproduced image. Therefore, it is necessary to sacrifice the deterioration of the image quality of the reproduced image for long-time recording. However, in the digital VTR which is a digital recording, the deterioration of the C / N of the reproduced signal due to the narrowing of the track pitch leads to an increase in the code error rate of the reproduced digital information, and this code error rate When the error correction circuit exceeds the correction capability, the reproduced image suddenly breaks down.

On the other hand, if the code error rate is within the correction range of the code error correction circuit, even if the track pitch is further widened to improve the C / N of the reproduced signal, the quality of the reproduced video cannot be expected to improve. Therefore, in the digital VTR, the track pitch is set near the limit of the code error rate within the range that does not exceed the correction capability of the code error correction circuit, and the recording information amount is reduced by increasing the compression rate for long-time recording, It is common to deal with the problem without narrowing the track pitch.
Hereinafter, a method of reducing the amount of recorded information by increasing the compression rate more than usual and realizing long-time recording without narrowing the track pitch is referred to as first long-time recording.

However, the magnetic tape, the magnetic head,
The track pitch for obtaining an equivalent C / N tends to be narrowed by improving the performance of the reproduction signal detection circuit and the like. That is,
When the performances of the magnetic tape, the magnetic head, the reproduction signal detection circuit, and the like are improved, the track pitch is narrowed without increasing the compression rate, and it becomes possible to cope with long-time recording without deteriorating the image quality of the reproduced video. Hereinafter, a method of realizing the long-time recording by narrowing the track pitch with the normal compression ratio as compared with the normal compression is referred to as the second long-time recording.

For example, in a tape which can be recorded at a normal compression rate for 1 hour at a normal track pitch, if the track pitch is narrowed to ⅔, the normal compression rate is 1.5 hours, and the compression rate is doubled, for example. When used in combination with the first long time recording described above, recording for 3 hours becomes possible. Hereinafter, the long time recording in which the first long time recording and the second long time recording are used together is referred to as the third long time recording.

Therefore, in the method disclosed in Japanese Patent Laid-Open No. 6-195614, when the normal recording with the normal track pitch and the first, second, and third long-time recording are dealt with, for example, voice is recorded with the normal track pitch. The track pitch of one track immediately after the after-recording for re-recording only the signal or the over-recording for overwriting the tracks already recorded for each track is narrower than the other tracks as shown in FIGS. 11 and 12. Although it does not occur (However, since the effective head width of the magnetic head is generally set wider than the track pitch, it is somewhat narrower than other tracks.) After-recording or insertion in the second and third long-time recording The track pitch of one track immediately after recording is higher than that of other tracks as shown in FIGS. 13 and 14. It is narrowed to the end.

FIG. 13 is a diagram showing a track pattern near the end of the insertion recording when the insertion recording is performed in the second long recording, and FIG. 14 shows the insertion recording in the third long recording. FIG. 6 is a diagram showing a track pattern near the end of insertion recording when performed.

The track pitch (TpX) of one track immediately after the after-recording or the insertion recording in the second and third long-time recording is expressed by the following equation.

TpX = 2Tp-Hw Tp: Track pitch in the second and third long-time recording modes Hw: Effective head width of the magnetic head According to the above equation, the effective head width of the magnetic head is 2/3. When the second or third long time recording is performed at the track pitch,
TpX is ⅓ of the effective head width of the magnetic head, that is, half of the track pitch of other tracks, and the track pitch is further narrowed to make the second or third long time at the track pitch of half the effective head width of the magnetic head. When recording, T
pX becomes 0.

This is because the C / N at the time of reproducing one track immediately after after-recording or insertion recording is
This means that the quality is extremely worse than that of other tracks. For example, when a video is inserted and recorded, the reproduced video is highly likely to be destroyed at the moment when the video that is inserted and recorded is switched to the video before the insertion.

In a digital VTR for digitally recording audio and video, there is almost no deterioration of audio and video due to dubbing, which is very advantageous for editing such as after-recording and insertion recording. The problem that the track pitch of one track immediately after performing after-recording or insertion recording during long-time recording becomes extremely narrower than that of other tracks can fully utilize the above-mentioned advantage of editing. It means that it does not exist, and significantly restricts the function.

[0014]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a magnetic head A and a magnetic head A and a magnetic head A and a magnetic head B having different azimuth angles which are arranged adjacent to each other. In addition to the magnetic head C having the same azimuth angle, a magnetic head D having the same azimuth angle as the magnetic head A and having an effective head width narrower than the other heads on the opposite side of the magnetic head B with the magnetic head A interposed therebetween. The magnetic head D is provided instead of the magnetic head A only when performing the second and third long-time recording with a narrowed track pitch.

By only adding one magnetic head for the second and third long-time recording with a narrowed track pitch, the track pitch of one track immediately after the after-recording or the insertion recording is not narrowed, Normal recording mode to record at a normal compression rate with a normal track pitch,
A first long-time recording mode for recording at a higher compression ratio than usual with a normal track pitch, a second long-time recording mode for recording at a normal compression ratio by narrowing the track pitch, first
It becomes possible to correspond to four modes of the third long-time recording mode in which both the long-time recording and the second long-time recording are used together, and a great added value can be added.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of a digital information recording / reproducing apparatus showing an embodiment of the present invention. In FIG. 1, 1 is a compression coding means for normal recording that compresses a video signal at a normal compression rate, and 2 is a first compression code for long-time recording that compresses a video signal at a compression rate that is twice the normal compression rate. A changeover switch for selecting which of the compression coding means 1, 2 is used for recording, 3 is a voice signal coding means for coding a voice signal, 5 is compression coded. Parity adding means for adding a parity for code error correction to a video signal and an encoded audio signal, and 6 is a digital modulation (for example, interleaved NR) suitable for magnetic recording.
The channel encoding means for performing ZI modulation), the channel encoding means 6 is for performing mode information of which mode is selected among the standard recording mode and the three types of long-term recording modes, and tracking control during reproduction. It also includes the function of adding the pilot signal of (1) by superimposing it by digitally controlling the DC component of the modulation signal or by adding it in an analog manner.

Reference numeral 7 is a changeover switch for switching between a recording mode for supplying a recording signal to the magnetic head and a reproducing mode for inputting a reproducing signal from the magnetic head, and 8 is a magnetic head for supplying a recording signal to any one of the four magnetic heads. And 4
Head selecting means for selecting which of the two magnetic heads a reproduction signal is to be input to, 9 is a rotary drum, 10a, 10b, 10c and 10d are magnetic heads provided on the circumferential side of the rotary drum 9, 11 Is a magnetic tape, 12 is a tape feed control means for controlling the feeding of the magnetic tape according to the standard recording mode and the three types of long-time recording modes. The tape feeding control means 12 detects a pilot signal to perform tracking. Tracking control means (ATF: Au) for finely adjusting the tape feeding speed so as to obtain the optimum state.
to Track Finding) is also included.

Further, although not shown, as another means for tracking control, a magnetic head is attached to the rotary drum so as to be movable in a direction perpendicular to the track scanning direction, and the position of the magnetic head is finely adjusted. To optimize tracking by DTF (Dynamic T
rack following) may be used. 13 is a capstan roller, 14 is a channel decoding means for demodulating a reproduction signal, and this channel decoding means 14 also has a function of detecting the mode information added at the time of recording.

Reference numeral 15 is a code error correcting means for detecting a code error of the demodulated reproduced signal by using the parity added at the time of recording and performing correction or correction processing, and 16 is a voice signal decoding for restoring a coded voice signal. The converting means 17 is a changeover switch for switching which of the following two compression decoding means is used for decoding the video signal based on the mode information input from the channel decoding means 14, and 18 is a normal compression. A compression / decoding means for normal recording, which decodes a reproduction signal compression-encoded at a rate, and 19 for a first long-time recording, which decodes a reproduction signal compression-encoded at a compression rate twice that of a normal recording rate. It is a compression and decoding means of.

In the present embodiment, the track pitch of the second and third long-time recording is 2 / the normal track pitch.
The case of 3 will be described. FIG. 2 is a layout view of the magnetic heads provided on the circumferential side of the rotary drum 9 of the present invention. The magnetic head 10a and the magnetic head 10b have different azimuth angles, and have an effective head width that is equal to or slightly wider than the track pitch for normal recording. Magnetic head 10c
Has the same azimuth angle as that of the magnetic head 10b arranged 180 ° opposite to the magnetic head 10a.
The effective head width is the same as a and 10b.

The magnetic head 10d has the same azimuth angle as that of the magnetic head 10a, but the effective head width is narrower than that of the other magnetic heads, and the track pitch is the same as or slightly wider than the track pitches of the second and third long-time recording. That is, in the case of this embodiment, the effective head width is ⅔ of the track pitch for normal recording or slightly wider than that.

In the present embodiment, the track pitch of the second and third long-time recording is 2 / the normal track pitch.
3, but it can be applied to other ratios. For example, when the track pitch of the second and third long-time recording is set to 1/2 of the normal track pitch, the effective head width of the magnetic head 10d is set to 1/2 of the track pitch of the normal recording or slightly wider. Just set it.

FIG. 3 shows the track format of this embodiment. The ATF area 20 is an area in which a signal for the magnetic head to properly scan (tracking is adjusted) on the track is recorded. When the after recording or the insertion recording is performed, the ATF area 20 is not overwritten and the area is reproduced for tracking. Record while matching. Audio is recorded in the audio area 22, video is recorded in the video area 24, and additional information is recorded in the additional information area 26. Between these areas, a GAP 21 for preventing overwriting of other areas during after-recording or the like, 23 and 25 are provided.

Next, description will be made on examples of performing the insert recording in the standard recording and the three types of long-time recording modes, respectively.

In the standard recording mode, the video signal is compression encoded by the compression encoding means 1 for normal recording. On the other hand, the audio signal is input to the audio signal encoding means 4 and encoded by, for example, 4-channel stereo. The compression-encoded video signal passes through the change-over switch 3, and the parity adding means 5 adds a parity for code error correction together with the encoded voice signal, and the channel-encoding means 6 digitally modulates the change-over switch 7. It is passed and input to the head selection means 8. The timing of head selection in the standard recording mode is shown in FIG.

The head selecting means 8 alternately outputs the recording signal to the magnetic head 10a and the magnetic head 1 every half rotation of the rotary drum 9.
Record by feeding to 0c. At this time, the tape feeding control means 12 controls the rotation of the capstan roller 13 so that the tape feeding speed in the standard recording mode is achieved.

In the case of the first long-time recording mode, the video signal is compression-encoded by the first long-time compression encoding means 2. On the other hand, the audio signal is input to the audio signal encoding means 4 and encoded by, for example, 2-channel stereo, which has half the data amount of the standard recording mode. The compression-encoded video signal passes through the change-over switch 3, and the parity adding means 5 adds a parity for code error correction together with the encoded voice signal, and the channel-encoding means 6 digitally modulates the change-over switch 7. It is passed and input to the head selection means 8. The timing of head selection in the first long-time recording mode is shown in b of FIG.

The head selecting means 8 alternates the recording signal with the magnetic head 10a and the magnetic head 1 every one rotation of the rotary drum 9.
Record by feeding to 0b. At this time, the tape feed control means 12 controls the rotation of the capstan roller 13 so that the tape feed speed in the first long-time recording mode is 1/2 of the standard recording mode.

In the case of the second long-time recording mode, the video signal is compression-encoded using the compression-encoding means 1 for normal recording. On the other hand, the audio signal is input to the audio signal encoding means 4 and encoded by, for example, 4-channel stereo.

The compression-encoded video signal passes through the changeover switch 3, the coded audio signal is added with a parity for code error correction by the parity adding means 5, the digital signal is modulated by the channel encoding means 6, and the video signal is switched. It is passed through the switch 7 and input to the head selecting means 8. The timing of head selection in the second long-time recording mode is shown in FIG.

The head selecting means 8 alternately outputs the recording signal to the magnetic head 10a and the magnetic head 1 every half rotation of the rotary drum 9.
0c for recording, and only the last track of the inserted recording is recorded in place of the magnetic head 10a.
d is used. At this time, the tape feed control means 12 controls the rotation of the capstan roller 13 so that the tape feed speed in the second long-time recording mode is 2/3 of the standard recording mode.

In the case of the third long-time recording mode, the video signal is compression-encoded by using the first long-time recording compression encoding means 2. On the other hand, the audio signal is input to the audio signal encoding means 4 and encoded by, for example, 2-channel stereo, which has half the data amount of the standard recording mode. The compression-encoded video signal passes through the change-over switch 3, and the parity adding means 5 adds a parity for code error correction together with the encoded voice signal, and the channel-encoding means 6 digitally modulates the change-over switch 7. It is passed and input to the head selection means 8.

The timing of head selection in the third long-time recording mode is shown in d of FIG. The head selecting means 8 records the recording signal by alternately supplying the recording signal to the magnetic head 10a and the magnetic head 10b every one rotation of the rotary drum 9, and the magnetic head 10d is used instead of the magnetic head 10a only in the last track of the insertion recording. To use. At this time, the tape feed control means 12 controls the rotation of the capstan roller 13 so that the tape feed speed in the third long-time recording mode becomes 1/3 of the standard recording mode.

FIG. 5 shows a track pattern recorded in the second long time recording mode, and FIG. 6 shows a track pattern recorded in the third long time recording mode. In addition,
Since the track patterns recorded in the standard recording mode and the first long-time recording mode are the same as the track patterns shown in the conventional example (FIGS. 11 and 12), the illustration thereof is omitted.

Next, the operation during reproduction will be described. At the time of reproduction, if it is not known in which mode the recording is performed, the reproduction signal reproduced alternately from the magnetic head 10a and the magnetic head 10c or the magnetic head 10a and the magnetic head 10b while the magnetic tape 11 is stopped or slightly fed. The channel decoding means 14 detects the included mode information, and based on the detected mode information, the tape feed control means 12 controls the rotation of the capstan roller 13 so that the tape feed speed becomes the same as that at the time of recording.

When reproducing the tape recorded in the normal recording mode and the second long-time recording mode, the head selecting means 8 alternately selects the magnetic heads 10a and 10c as in the recording. The reproduced video signal is restored using the compression / decoding means 18 for normal recording, and the audio signal is restored to, for example, 4-channel stereo by the audio signal decoding means 16.

When reproducing the tape recorded in the first long time recording mode and the third long time recording mode, the head selecting means 8 alternately selects the magnetic heads 10a and 10b as in the recording. . The reproduced video signal is restored by using the first compression / decoding means 19 for long-time recording, and the audio signal is restored by the audio signal decoding means 16 to, for example, 2-channel stereo.

Here, when reproducing the tape recorded in the second and third long-time recording modes, the magnetic head 10d may be used instead of the magnetic head 10a, but the magnetic head 10d may be used. Since the effective head width is narrow, the reproduction signal level from the magnetic head becomes smaller than that of other magnetic heads, and the amount of data that can be detected from a track with the same azimuth angle is particularly large during special reproduction in which the magnetic head scans the track diagonally. It is disadvantageous because it decreases.

In the present embodiment, the magnetic head 10d is used instead of the magnetic head 10a only in the last track of the insertion recording in the second and third long time recording modes.
The same effect can be obtained by always using the magnetic head 10d instead of the magnetic head 10a. FIG. 7 shows a track pattern when the magnetic head 10d is always used in the second long time recording mode, and FIG. 8 shows a track pattern when the magnetic head 10d is always used in the third long time recording mode.

Although the insertion recording has been described in the present embodiment, the present invention can also obtain the same effect when rewriting a part of the track such as after recording. As an example, FIG. 9 shows a track pattern in the vicinity of the end of after-recording when audio signal after-recording is performed in the third long-time recording mode. In FIG. 9, the magnetic head 1 is used instead of the magnetic head 10a only in the last track of after recording.
The case where 0d is used is shown.

Further, in the present embodiment, the recording data amount of the first and third long-time recording is set to 1/2 of the normal recording, but this can be expanded to 1 / N (N is an integer of 2 or more). FIG.
As an example, 0 shows the timing of head selection in the third long-time recording mode when N = 3 and N = 4.

[0042]

As described above, according to the digital information recording / reproducing apparatus of the present invention, the magnetic heads A and B which are adjacently arranged and have different azimuth angles and the magnetic head B which is arranged at the position opposite to the magnetic heads A and B are arranged. In addition to the magnetic head C having the same azimuth angle, a magnetic head D having the same azimuth angle as the magnetic head A and having an effective head width narrower than the other heads on the opposite side of the magnetic head B with the magnetic head A interposed therebetween. The magnetic head D is used instead of the magnetic head A only when performing the second and third long-time recording in which the track pitch is narrowed and is provided on the circumferential side of the rotary drum. It is possible to support four modes of normal recording, first long-term recording, second long-term recording, and third long-term recording without narrowing the track pitch of one track.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital information recording / reproducing apparatus showing an embodiment of the present invention.

FIG. 2 is a layout view of magnetic heads provided on the circumferential side of the rotary drum of the present invention.

FIG. 3 is an explanatory diagram showing an example of a track format.

FIG. 4 is a timing chart of head selection in each mode of the present invention.

FIG. 5 is an explanatory diagram showing a track pattern during second long-time recording according to the present invention.

FIG. 6 is an explanatory diagram showing a track pattern at the time of third long-time recording of the present invention.

FIG. 7 shows the magnetic head 10 during the second long time recording of the present invention.
It is explanatory drawing which shows the track pattern when d is always used.

FIG. 8 is a magnetic head 10 in the third long-time recording of the present invention.
It is explanatory drawing which shows the track pattern when d is always used.

FIG. 9 is an explanatory diagram showing a track pattern at the time of after-recording an audio signal during the third long-time recording of the present invention.

FIG. 10 is a timing chart of head selection when the recording data amount of the third long-time recording of the present invention is ⅓ and ¼ of the normal recording.

FIG. 11 is an explanatory diagram showing a track pattern at the time of normal recording in a conventional example.

FIG. 12 is an explanatory diagram showing a track pattern during first long-time recording in a conventional example.

FIG. 13 is an explanatory diagram showing a track pattern at the time of second long-time recording in the conventional example.

FIG. 14 is an explanatory diagram showing a track pattern at the time of third long-time recording in the conventional example.

FIG. 15 is a layout diagram of magnetic heads provided on the circumferential side of a conventional rotary drum.

[Explanation of symbols]

 1 Compression Recording Means for Normal Recording 2 First Compression Coding Means for Long Time Recording 3 Changeover Switch 4 Audio Signal Coding Means 5 Parity Adding Means 6 Channel Encoding Means 7 Changeover Switches 8 Head Selection Means 9 Rotating Drum 10a Magnetic head A 10b Magnetic head B 10c Magnetic head C 10d Magnetic head D 11 Magnetic tape 12 Tape feed control means 13 Pinch roller 14 Channel decoding means 15 Code error correction means 16 Voice signal decoding means 17 Changeover switch 18 First long time Recording / decoding means for recording 19 Compression / decoding means for normal recording 20 ATF area 21 GAP 22 Audio area 23 GAP 24 Video area 25 GAP 26 Additional information area

Claims (3)

[Claims] 1. A digital information recording / reproducing apparatus in which a magnetic tape is wound around a rotary drum, and a magnetic head mounted on the rotary drum records and reproduces digital information in a helical track shape. Of the first and second magnetic heads having substantially the same value, and the first and second magnetic heads.
A third magnetic head having the same azimuth angle and substantially the same effective head width as the second magnetic head arranged in the opposite position to the third magnetic head.
Of the first magnetic head and the first magnetic head that is adjacently arranged on the opposite side of the second magnetic head with the first magnetic head sandwiched therebetween, and the effective head width is the same as that of the other magnetic head. A narrow and narrow fourth magnetic head is provided on the circumferential side of the rotating drum, and at the time of a long-time recording mode in which the track pitch is narrowed by making the feeding speed of the magnetic tape slower than usual, at least immediately before the end of recording. The digital information recording / reproducing apparatus is characterized in that the fourth magnetic head is used instead of the first magnetic head to record digital information on the track. 2. The digital information according to claim 1, wherein the fourth magnetic head is always used in place of the first magnetic head in a long-time recording mode in which the track pitch is narrowed for recording. Recording / playback device. 3. A long-time recording having a plurality of compression-encoding means having different compression rates and combined with a long-time recording with a high compression rate and a long-time recording with a narrowed track pitch. The digital information recording / reproducing apparatus according to claim 1 or 2, characterized in that: