JPH0485718A - Digital tape recorder - Google Patents

Abstract

PURPOSE:To record and reproduce both audio signal and video signal by tracing one part of a track recorded by 1st and 2nd heads with another pair of 2nd and 4th heads and recording a new track by overwriting. CONSTITUTION:The recorder is composed of the 1st-4th heads Ha-Hd arranged by holding their angular intervals of 90 deg., where their azimuth angles are selected to be different in azimuth respectively, and a gap length Ga of the heads Ha and Hc is selected to be a little over two times as long as a gap length Gc of the 2nd and 4th heads. Then, the head Hd is fitted on a rotary drum 2 to have a prescribed step that is different from the heads Ha-Hc. By this method, since one part of a track Ta recorded by the head Ha is traced by the following head Hb, the one part of the track Ta is overwritten. Because of different azimuths of the individual heads Ha-Hd, high density recording is feasible.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is capable of recording both audio and video signals with one digital tape recorder without deteriorating both sound quality and image quality. The present invention relates to a digital tape recorder having a recording function that allows playback.

[Prior Art] By using a digital audio tape recorder (DAT) as a basic configuration and adding some circuit configuration to it, it is possible to record and reproduce not only audio signals but also video signals.

If such an AT-compliant tape recorder is called a digital tape recorder, it is preferable that this digital tape recorder can also record and reproduce both signals without deteriorating both sound quality and image quality.

As for video signals, high image compression processing technology that utilizes image correlation has been developed, so even if the amount of information is reduced, it can be recorded and reproduced without deteriorating its image quality.

On the other hand, simply reducing the number of bits of an audio signal degrades the sound quality.

[Problems to be Solved by the Invention] As described above, when configuring a digital tape recorder that is compliant with DAT, it is possible to record and play back video signals in addition to audio signals without deteriorating both their sound quality and image quality. Can not.

Furthermore, when recording and reproducing a video signal superimposed on an audio signal, if the audio signal is recorded in the upper 8 bits and the video signal is recorded in the remaining 8 bits, the audio signal and the video signal are recorded in the lower 8 bits. Since the video signals cannot be separated, it is not possible to after-record any of the signals.

The present invention takes these points into consideration and proposes a digital tape recorder that can record and reproduce audio and video signals without deteriorating both sound quality and image quality.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the present invention, first, second, third and fourth parts having different azimuths are arranged with an angular interval of 90 degrees from each other. It has a rotating magnetic head made up of heads, and regarding the tracks recorded by these heads, a part of the tracks recorded by the first and third heads is recorded by another pair of second and fourth heads. A fourth head is mounted on the rotating drum at a predetermined step with respect to the first to third heads so that a new track is overwritten and recorded by tracing, The second head records and reproduces audio signals, and the third and fourth heads record and reproduce video signals.

1 Effect] As shown in FIG.
The first to fourth heads H are arranged with an angular interval of degrees
It is composed of a=Hd.

When these four heads Ha=Hd are developed, their azimuth angles are selected so that each azimuth is different, as shown in FIG. First and third heads Ha, H
The gap length Ga of e is the second and fourth gap length G
It is selected to be more than twice as large as c.

Further, the fourth head Hd is mounted on the rotating drum 2 so as to have a predetermined step difference with respect to the first to third heads Ha=Hc.

By doing this, as shown in FIG. 3, the second head Hb that follows traces a part of the track Ta recorded by the first head Ha, so that a part of the track Ta is traced by the second head Hb that follows it. is overwritten.

Similarly, a portion of the track Tc formed by the third head Hc is overwritten by the trailing fourth head Hd, resulting in a track pattern as shown in FIG. 3.

The pitch of the tracks formed will be the same as that of the current DAT format, but since the azimuth of each head Ha to Hd will be different, high-density recording will be possible, and therefore the tape unit length and recording per unit of normal DAT will be shorter. The same amount of information can be recorded.

Therefore, if the audio signal conforms to the DAT format, it is recorded as 16-bit information as is, and the video signal is compressed using high compression technology and recorded, thereby improving the sound and image quality. Recording and reproduction can be performed without deteriorating both sides.

[Embodiment] Next, an example of the digital tape recorder according to the present invention will be described in detail with reference to FIG. 1 and subsequent figures.

FIGS. 1 and 2 show an example of the configuration of a rotating magnetic head 1 used in a digital tape recorder according to the present invention.

In the present invention, the rotary magnetic head 1 is composed of first to fourth heads Ha = Hd arranged at an angular interval of 90 degrees from each other.

The overlap angle θ of the magnetic tape 3 with respect to the rotating drum 2 is approximately 90 degrees, similar to the current DAT format.

In addition, the diameter of the rotating drum 2 and the rotation speed of the rotating drum 2 are the same as the current DAT format, and the magnetic tape 3
is twice as fast as the current DAT format.

As is clear from the developed view of the rotating magnetic head 1 shown in FIG. 2, the azimuths of the first and third healds Ha and Hc, which are arranged to face each other, are selected to be opposite to each other. . Similarly, the second and fourth heads Hb,
The azimuths of Hd can also be chosen to be opposite to each other. In this example, the azimuth angle is selected so that it is ±20 degrees even in the case of tilt.

Regarding the tracks recorded on these heads Ha to Hd, a part of the tracks Ta and Tc recorded by the first and third heads Ha and He are recorded by another pair of second and fourth heads HbHd. By tracing, the right half of track Ta and the left half of track Tc,
The gap lengths Ga and Gc and the mounting of the first to fourth heads Ha=Hd can be selected to have a step difference so that new tracks Tb and Td are respectively overwritten and recorded.

That is, in order to achieve such recording, the gap length Ga of the first and third heads Ha and He is set to be equal and approximately twice the current length, and the gap length Ga of the second and fourth heads is set to be equal.
The gap length Gc of the heads Hb and Hd is selected to be 1/2 of that. The fourth head Hd is mounted on the rotating drum 2 so that the first to third heads Ha=Hc are mounted on the opposite side to the reference plane.

The first and second heads Ha, Hb are used to record and reproduce audio signals, and the third and fourth heads He, Hd are used to record and reproduce video signals. This relationship may be reversed.

FIG. 3 shows an example of the track pattern on the tape that can be formed by the first to fourth heads Ha=Hd when the rotary magnetic head 1 is configured in this manner.

Here, arrows indicate the running direction of the magnetic tape 3 and the rotation direction of the rotary drum 2.

Since the first and third heads Ha and He are arranged with an angular interval of 180 degrees from each other, the third head Ha and He are adjacent to the track Ta formed by the first head Ha.
A track Tc is formed by the head He. In this case, track radius (track pitch) P a + P
c is approximately equal to the head gap length Ga.

On the other hand, the second head Hb is arranged at a position 90 degrees behind the first head Ha, and the fourth head Hd is located at a position 90 degrees behind the first head Ha.
The head Hc is located at a position 90 degrees behind the head Hc. Therefore, the second spatula FHb is connected to the first track T.
Since the right half of a is to be traced, a part (right half) of the track Ta is overwritten by the second head Hb, and a new track Tb (track radius is Pb) is formed here.

Similarly, a part (left half) of the track Tb is overwritten by the fourth head Hd, thereby forming a new track Td (track radius is Pd).

Here, the track widths Tb and Td conform to the DAT format.

At the same time as the audio signal digital data A-DATA and the video signal digital data .DATA are recorded, the subcode SUB and the tracking signal ATF are each recorded according to the current DAT format, similarly to the DAT.

In this case, for example, even when a video signal is not recorded, the subcode SUB and tracking signal ATF are recorded. This is for tracking when after-recording the audio signal.

Just before writing #I! FIG. 4 shows a situation in which the next track can be completely formed by overwriting the track that has been written.

When audio signals and video (No. 8) are recorded by such overwriting, the track pitch will be the same as the current D
The track pitch is the same as the AT format. The number of rotations of the rotating drum 2 is the same as that of the current DAT, and the running speed of the magnetic tape 3 is twice that of the current one, so the amount of information of audio and video signals that can be recorded in the same recording time is the same as that of the two-head system. This is twice as much as the current DAT.

Therefore, the same amount of information as the current two-head DAT can be recorded in the same recording time using the two-track recording format (with two-track intervals) for audio signals, and the transfer rate per unit time is therefore are also the same. Furthermore, by using high compression technology for video signals, the image quality will not deteriorate even if the video signals are compressed and recorded to the same amount of information as the audio signal or less.

With this, audio signals can be recorded and reproduced without deteriorating sound quality, and video signals can also be recorded and reproduced without deteriorating their image quality.

Furthermore, since the audio signal and the video signal are recorded on separate tracks, it is possible to perform after-recording for either signal. That is,
You can also after-record video signals, and you can also after-record audio signals.

FIG. 5 shows a digital tape recorder 10 according to the present invention.
FIG. 6 shows an example of the recording system, and FIG. 6 shows an example of the reproducing system.

The circuit configuration of this digital tape recorder 10 includes an audio signal recording system 10AR, an audio signal reproduction system 10AP, and a video signal recording system 30VR.
and a video signal reproduction system 30VP.

FIG. 5 shows details of the recording system for audio signals and video signals.

Let's start with the audio signal. The R channel and L channel audio signals are converted into digital audio signals of a predetermined number of bits by A/D converters 11 and 12, and this is supplied to the input interface 16 side via changeover switches 13 and 15.

The digital audio signal DA itself is supplied to one terminal of the changeover switch 13 via an interface 14, and therefore the changeover switch 13 is used as means for switching input sources.

A changeover switch 15 disposed at the rear stage is used to select a binary code signal (SCSI signal) generated by a personal computer or the like as an input source, and the details will be described later.

The digital audio signal that has passed through the input interface 16 is subjected to interleaving processing in a well-known manner in an interleaving processing circuit 17, and then error correction processing is performed in an encoding circuit 18.

Roughly speaking, after the bit data is converted in the 8/10 conversion circuit 19, the mixer 20 converts the bit data to the terminal 21.
It can be combined with the tracking signal ATF and subcode SUB supplied from the subcode SUB. The output is supplied to a changeover switch 26 via a driver 22.

A delay circuit 27 is provided on one side of the changeover switch 26,
Digital audio signals are alternately supplied to this delay circuit 27 at a predetermined period.

That is, since digital audio No. 4 is subject to interleaving processing, it is necessary to arrange the next unit signal group after a predetermined processing time as shown in FIG. 7B.

On the other hand, since the digital audio signal must be recorded by the adjacent first and second heads Ha and Hb, the digital audio signal supplied to the second head Hb can be supplied as is in real time, but the first head Ha It is necessary to delay the digital audio signal supplied to the 174 rotation period.

Therefore, a delay circuit 27 as shown in FIG. 5 is provided, and the changeover switch 26 is controlled by the switching pulse SPa shown in FIG. (Fig. 7, A and B).

The delayed output and the non-delayed output are alternately switched by a changeover switch 28, and then selectively supplied to the first and second heads Ha and Hb via a changeover switch 23 at a subsequent stage.

Here, the changeover switches 23 and 28 are also sequentially and alternately switched by the switching pulse SPa shown in Figure 7.

Further, the first and second heads Ha + Hb are provided with changeover switches 24 and 25, and the switching states thereof are controlled according to the recording/reproducing mode.

The audio signals reproduced by the first and second heads Ha and Hb are transmitted to an audio signal reproduction system 10.
After being supplied to the AP, the R channel and L channel analog audio signals are reproduced, and the digital audio signal DA is output.

Next, the video signal recording system 30VR will be explained.

The video signal V is supplied to a high compression encoding circuit (DVI) 31 and is highly compressed and encoded to 1/160 in this example. This is converted into a DAT format by the output circuit 32, and is supplied to the input interface 38 via the changeover switch 33.

A 5C8I signal is supplied to one terminal of the changeover switch 33 via an interface 34 to a distribution circuit 35,
The video signal is divided into an audio signal and a video signal, and the fully distributed video signal is sent to a changeover switch 33 for switching the input mode.
Enter.

The format-converted digital video signal passes through the input interface 38 and undergoes the same processing as normal DAT conversion processing. That is, first, interleaving processing is performed in the interleaving processing circuit 39, error correction processing is performed in the encoding circuit 40, and then bit conversion processing is performed in the 10.8 conversion circuit 141. Thereafter, it is combined with the tracking signal ATF and the subcode SUB in a mixer 49. The output is supplied to a changeover switch 46 via a driver 42.

A delay circuit 47 is provided on one side of the changeover switch 46,
Digital audio signals are alternately supplied to this delay circuit 47 at a predetermined period.

The reason for providing the delay circuit 47 is as follows.

As is clear from the track pattern in FIG. 3, in order to perform high-density recording, the azimuths of the head between adjacent tracks must be different from each other. Since the second head Hb has a negative azimuth, the azimuth of the adjacent track Td needs to be a positive azimuth. The fourth head Hd forms this track Td.

On the other hand, although the signal is recorded by the third head HC after the second head Hb, judging from the time series of the video signal shown in FIG. 7C, the video signal q is recorded in real time. Therefore, the video signal r recorded by the fourth head Hd must be delayed by 3/4 rotation period.

For this reason, the delay circuit 47 for 3/4 rotation period
is provided so that the video signal r is delayed by 3/4 rotation period and output.

Therefore, as shown in FIG. 5, changeover switches 46 and 48 are provided before and after the delay circuit 47, respectively.
It is controlled by the switching pulse SPV shown in Figure E.

The delayed output and the non-delayed output are alternately switched by the changeover switch 48 and then alternately supplied to the third and fourth heads Hc*Hd via the changeover switch 43 at the subsequent stage (see FIG. 7). The switching pulse SPv shown in FIG. 7E is also supplied to the changeover switch 43.

Note that 44 and 45 are switches that can be changed according to the recording/reproducing mode.

The digital video signals reproduced by the third and fourth heads Hc and Hd are supplied to a video signal reproduction thread 30VP, from which a video signal or a 5CSI signal is output.

FIG. 6 shows an example of the reproduction system of DATl 0, which will be explained starting with the audio signal system.

The digital audio signals reproduced by the first and second heads Ha+Hb are sent to preamplifiers 51.52 and equalizer amplifiers 53.54 and 1, respectively.
The signal is supplied to a changeover switch 55 via a delay circuit 50 having a delay time of /4 drum rotations (FIGS. 8A and 8B).
56 is a circuit for detecting the tracking signal ATF, and a tracking error signal is formed from each reproduction output of the first and third heads Ha and Hc.

A switching pulse SPa as shown in Figure 8 is supplied to the changeover switch 55 through a terminal 57, and R channel and L channel digital audio signals are alternately output.

This digital audio signal is transmitted to the high frequency reproduction circuit 58.
1. At the same time, a reference clock is regenerated from the reproduced high-frequency signal in a clock regeneration circuit 59, and the output thereof is supplied to a decoding circuit 60 where error correction processing is performed, followed by deinterleaving processing. Deinterleaving processing is performed in circuit 61.

The output is roughly supplied to a D/A converter 65.66 through an output interface 62 and a changeover switch 63.64, and is converted into an analog audio signal (L channel, R channel).

Further, when the input source is digital audio No. 48, the digital audio signal is outputted via the interface 67.

On the other hand, the digital video signals reproduced by the third and fourth heads He, Hd are connected to the video signal reproduction system 30V.
The signal is supplied to the delay circuit 76 through the preamplifiers 71 and 72 and equalizer amplifiers 73 and 74 that make up P, and is delayed by 3/4 drum rotation, and then is completely supplied to the changeover switch 751!1 (FIG. 8A , C).

The switching pulse SPv shown in FIG. 8E is supplied to the changeover switch 75 from its terminal 77, so that the reproduced video signals from the third and fourth heads Hc+Hd can be outputted alternately.

This signal is converted into a 1°0 signal by a high frequency regeneration circuit 78, and the reference clock is regenerated by a clock regeneration circuit 79. After error correction processing is performed in a decoding circuit 80, deinterleaving is performed. The signal is supplied to a processing circuit 981 and subjected to deinterleaving processing.

The output is supplied to an output circuit 84 via an output interface 82 and a changeover switch 83, and is also supplied to a decompression circuit (DVI) 85, where the compressed video signal is converted into a video signal having the original time axis. Output.

If the reproduced video signal is an SC8I signal, it is supplied to the coupling circuit 86, where the video signal and the audio signal reproduced from the audio signal reproduction system 10AP are combined, and this is output via the interface 87. will be done.

As described above, by using the head configuration as shown in FIG. 1, a digital tape recorder compliant with the DAT format can be constructed.

By recording the audio signal and video No. 48 on separate tracks as shown in FIG. 3, it becomes possible to perform after-recording of the audio signal or video No. 48.

[Effects of the Invention] As explained above, in the present invention, by using a rotating magnetic head having a special configuration, it is possible to record and reproduce both audio signals and video signals.

Moreover, in this case, the amount of recorded information of the audio signal will be 1/2 that of the current DAT format, but the number of A/D conversion bits will not change, so it is possible to reproduce the same sound quality as the current DAT format.

As for the video signal, high compression processing technology can be employed, and as a result of the above, it has the characteristic of being able to record and reproduce without deteriorating both sound quality and image quality.

After-recording is also possible.

10AP ・ 30VR・ 30VP　・ Ha～Hd・ ・Audio signal reproduction system ・Video signal recording system ・Video signal reproduction system ・First to fourth heads

[Brief explanation of drawings]

FIG. 1 is a block diagram of a rotary magnetic head suitable for use in a digital tape recorder according to the present invention, FIG. 2 is a developed view thereof, and FIGS. 3 and 4 show a track pattern formed by this rotary magnetic head. The explanatory diagram, Fig. 5, is a system diagram showing an example of the recording system of the digital tape recorder according to the present invention, and Fig. 6 is a system diagram showing an example of the playback system.
FIGS. 7 and 8 are waveform diagrams for explaining the operation. l φ 2 ・ 3 Fist 10 ・ 1 0AR ・Rotating magnetic head・Rotating drum・Magnetic tape・Digital tape recorder・Audio signal recording system Configuration of rotating shop front head 1 Fig. 1Hν)-1c-1tL Soft-mouth magnetic head 1 development diagram Figure 2 Truck nog turn Figure 4

Claims (1)

[Claims] (1) It has a rotating magnetic head composed of first, second, third, and fourth heads with different azimuths, which are arranged at an angular interval of 90 degrees from each other, and tracks are recorded by these heads. Regarding the above, the second and fourth heads of the other pair trace a part of the track recorded by the first and third heads, and a new track is overwritten and recorded. A fourth head is mounted on the rotating drum at a predetermined step with respect to the first to third heads, audio signals are recorded and played back by the first and second heads, and the third and fourth heads A digital tape recorder characterized in that a video signal is recorded and played back.