JP2644283B2 - Rotary head type recording or reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rotary head type recording or reproducing apparatus.

[Prior Art] As is conventionally known, in an apparatus that handles a high-speed digital signal such as a video signal, in order to reduce a bit rate per system by distributing the signal to a plurality of systems, It is necessary to mount a plurality of heads that come into contact with the tape simultaneously with one rotating head.

8 to 10 show a conventional example of a device for distributing signals into four systems. Here, FIG. 8 and FIG. 9 are a top view and a side developed view showing the arrangement of the rotary head. In the figure, 1 is a rotary drum, 2 is a magnetic tape, and A to H are heads respectively. As shown in the figure, the heads A to H mounted on the outer periphery of the rotary drum 1 at four intervals of θ ゜ and at the position of the step X sequentially rotate the magnetic tape 2 with the rotation of the rotary drum 1.
, But four or more are always in contact at the same time,
Four signals can be recorded or reproduced.

In such a configuration, by sending the magnetic tape 2 at a predetermined speed V _T, track pattern having a uniform track pitch T _P (see FIG. 10) is formed. Here, by setting azimuth angles of + α ゜ and −α ゜ with respect to the adjacent head, a guard band is eliminated by using azimuth loss and a high recording density is obtained.

[Problems to be Solved by the Invention] By the way, there is a demand to change the bit rate of a digital signal to be recorded and reproduced. For example, in the case of a video signal, various band compression techniques are known, and it is possible to reduce the data amount while minimizing the deterioration of the image quality. Recording and reproduction can be realized. A mode for performing such recording and reproduction is hereinafter referred to as a long time mode.

Therefore, in the above-described conventional example, in order to increase the recording time by changing the bit rate, it is necessary to set the tape speed to 1/2 and simultaneously record two signals using only the heads A, B, E, and F. Conceivable.

However, when the four heads A, B, E, and F are used, the track pattern is as shown in FIG. 11 (the figure shows the case of θ = 13.5 °), and the track pitch is not uniform.

In general, the track pitch described by the two heads mounted with a step of θ ° spacing and X is the total number of heads as the 2N, when the track pitch when the tape speed V _T and T _P, when the tape speed is (1 / n) V _T is (See FIG. 12). Here, the one-dot chain line in FIG. 12 indicates the head trajectory at the tape speed V _T , and the broken line indicates the head trajectory at the tape speed (1 / n) V _T , and the vertical lines p and q and the chain line Alternatively, the intersection with the dashed line indicates the step on the drum and the actual track pitch, respectively. That is, the track pitch is However, there is a disadvantage that the output is reduced and the S / N is deteriorated.

In particular, when recording a digital signal, it is known that if the S / N ratio is deteriorated by 1 dB, the data error rate is increased by about 10 times, and the influence is large.

Further, the required at the time of pre-narrow track pitch T _P 'S / N
Is obtained, the average track pitch is _TP , so that extra tape is consumed. That is, the ratio is T _P / T _P ′ times (1.15 times in the above-described example), and the recording density is low.

Therefore, an object of the present invention is to provide an S / S
It is an object of the present invention to provide a magnetic recording / reproducing apparatus capable of performing high-density recording by reducing a required tape amount without causing N deterioration.

Means for Solving the Problems To achieve the above object, according to the present invention, in a rotary head type recording or reproducing apparatus for recording or reproducing signals of a plurality of systems simultaneously, a recording medium is conveyed at a first speed. The number of heads used in the second mode for transporting the recording medium at a second speed lower than the first speed is made smaller than the number of heads used in the first mode, and a pair of heads used only in the first mode is used. The shift amount of the trace position between the pair of rotary heads used in the first and second modes is made larger than the shift amount of the trace position between the rotary heads.

[Operation] With the above configuration, the average value of the shift amount of the trace position of the head can be suppressed to a necessary minimum, and the minimum track width can be kept large. Accordingly, even when the recording medium is conveyed at any of the first and second speeds, high-density recording can be realized without signal deterioration.

EXAMPLES Hereinafter, the present invention will be described in detail based on examples.

First, a DVTR (Digital Video Tape Recorder) according to a first embodiment of the present invention will be described with reference to FIGS.
Will be described. Here, FIG. 1 is a track pattern diagram at the time of the tape speed V _T ^* (standard mode), FIG. 2 is a side view of the rotary drum used in this embodiment, FIG. The figure is a track pattern diagram at the time of the tape speed (1/2) V _T ^* (long time mode). The top view of the above-mentioned rotary drum is the same as the conventional example shown in FIG.

In the present embodiment, as shown in FIG.
A step only X ₁ between the between and E and F of B, other X
And The step X _1, X, as shown in respectively Fig. 3 ^{_{(1 / n) V T *}} ( here, n = 2), the size T _P becomes the track pitch is obtained when sending the tape at V _T ^* That's it. The V _T ^* is the speed of the tape when some of the fast average track pitch T _P ^* than tape speed V _T at the time of the average track pitch T _P.

When the tape is fed at the speed V _T ^* using the rotary head and the apparatus in the standard mode (first mode), the track pattern shown in FIG. 1 is obtained. That becomes a track only T _P 'becomes pitch drawn by the head A and E used in the long-time mode (second mode), the other is T _P
Pitch.

Here, from FIG. On the other hand, T _P ^* is the erase the 'T _P from two equations on + 3T _P' from the average track pitch 4T _P ^{* =} T _P Request T _P ^*, That is, Now, assuming that N = 4 and n = 2, the same θ13 = 13.
5 ゜ Becomes

The tape feed speed is 1 / 2V _T ^*, and four heads A, B, E, and F
When only two systems are used for the parallel recording, the track pattern shown in FIG. 4 is obtained. Here, the track of the head A and E track pitch T _P as described above, since the track of the head B and F average track pitch of T _P ^*, with 2T _P ^* -T _P becomes pitch (this example , About 1.0
78T _P ).

As described above, in the above-described conventional example, the tape consumption is increased by about 15% in order to obtain the same minimum track pitch of T _P , whereas in the present embodiment, the increase is required by about 3.9%.

FIG. 5 is a side developed view of the rotary drum according to the VTR of the second embodiment. In this embodiment, the heads A and B, B
And C, and step C and D and X _1, head E and F, F and G, the step between the G and H and X, and the step of the head A and E in the X '.

With such a step, the tracks of the heads A, B, and C are at the pitch T when the tape is in the standard mode, that is, when the tape speed is V _T ^*.
_P ′ and at other times T _P.

Therefore, the step X ′ is X ′ = 1.5 × (T _P ′ −T _P )
Is set to

As in the first embodiment, 8T _P ^* = 3 T _P '+ 5 T _P Now, if N = 4, n = 2, θ2 = 13.5 ゜, On the other hand, when the long-time mode, that is, the tape speed is set to (1/2) V _T ^* , the track pitches obtained by intermittently using only the four heads A, B, C, and D are the heads A, B, and C. Is T _P , and for head D is (4T _P ^* −3 T _P ).

Also in the case of the present embodiment, the tape consumption can be increased by about 6%.

Although the above description has been made for the case of N = 4, n = 2, θ ゜ = 13.5 °, the present invention is also applicable to various other combinations of numerical values. Also, as shown in FIG. 8 and FIG. 9, even when the mounting step of the head is constant, the mounting phase is made different so that the present invention can be applied to reduce the tape consumption similarly. Can be.
In other words, the steps and phases between the heads used in the slower tape speed mode are set according to the minimum required track pitch in the mode, and the steps between the heads not used in the above mode are set. The tape can be used effectively by setting the step and the phase so that the pitch and the phase have the minimum necessary pitch according to the mode to be used.

FIG. 6 is a block diagram showing a head switching unit according to an embodiment of the present invention, and FIG. 7 is a diagram showing switching signals SWA to SWD and mode signals SP / LP (standard mode / long time mode) used for this. 5 is a timing chart of R / P (recording / reproducing).

As shown in FIG. 6, the input signal is A / D converted by the A / D converter 20.
After the conversion, the modulation unit 22 performs processing such as encoding, addition of an error correction code, and DC component suppression modulation. Then, the signals are converted into four or two parallel signals corresponding to the mode signal SP / LP, and further supplied to each head.

The timing is determined by switching signals SWA to SWD generated based on the phase of the rotating drum, as shown in FIG.
Is determined by

The above is the operation at the time of recording, and at the time of reproduction, the mode of the recorded signal is determined by a mode detection unit (not shown), and the output from each head is corresponding to the mode signal SP / LP generated thereby. The output signal is obtained by demodulation and D / A.

[Effects of the Invention] As described above, in the present invention, the shift amount of the trace position between the heads used in both the first and second modes is
The track pitch can be set even at two or more different tape speeds by setting a large value so as to be equal to or more than the minimum value required in the second mode and a small value so as to be equal to or more than the minimum value required in the first mode. While ensuring the minimum value of
An increase in tape consumption can be minimized and a high recording density can be obtained.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a DVTR according to the present invention.
FIG. 2 is a side view of the rotary drum according to the first embodiment of the present invention, FIG. 3 is an explanatory view of a track pitch, and FIG. FIG. 5 is a side view of the rotary head according to the second embodiment, FIG. 6 is a block diagram showing a head switching unit according to the embodiment of the present invention, and FIG. FIG. 6 is a waveform diagram showing the operation, and FIGS. 8 to 12 are diagrams for explaining the prior art. 1 ...... rotary drum, 2 ...... tapes, A to H ...... rotary head, V _H ...... rotational speed of the rotary head, V _T, V _T '...... tape feed _{speed, T P, T P',} T P ^* ... track pitch, X, X ', X ₁ ... step between heads, θ ゜ ... angle between heads.

Claims (1)

(57) [Claims] In a rotary head type recording or reproducing apparatus for simultaneously recording or reproducing signals of a plurality of systems, the first speed is determined by the number of heads used in a first mode for conveying a recording medium at a first speed. The number of heads used in the second mode for conveying the recording medium at a lower second speed is reduced, and the amount of trace position shift between a pair of rotary heads used only in the first mode is determined by the first and second modes. A rotary head type recording or reproducing apparatus characterized in that a shift amount of a trace position between a pair of rotary heads used in both of the second modes is increased.