JPH01277304A - Rotary head type recording or reproducing device - Google Patents

Abstract

PURPOSE:To attain recording/reproducing based on the same track pitch independently of a change in a tape speed by arranging 2N 1st azimuth heads, N 2nd azimuth heads and N 3rd azimuth heads on a rotary head in a specific order. CONSTITUTION:The 1st azimuth (0 deg.) heads A1-A4, the 2nd azimuth (+alpha deg.) heads B1, B2 and the 3rd azimuth (-alpha deg.) heads C1, C2 are arranged on the rotary drum 1 at an equal interval in the order of A1, C1, A2, B2, A3, C2, A4, and B1. A magnetic tape 3 is carried at a speed VT and four out of eight heads which are brought simultaneously into contact with the tape 3 are successively selected to record four system signals. When the tape speed is switched to 1/2 VT and two out of the four heads B1, B2, C1, C2 are successively selected to record two system signals. Both the SN ratio and frequency of recorded/ reproduced signals are not changed. Consequently, recording/reproducing based on the same track pitch can be attained even in modes having different tape speeds.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a rotary head type recording or reproducing device, which is suitable for recording and reproducing digital signals, for example. It is related to the device.

[Prior Art] As has been known in the past, in devices that record and reproduce high-speed and large amounts of digital signals such as video signals,
In order to reduce the bit rate per signal system by distributing signals to a plurality of heads, it is necessary to mount a large number of heads in contact with the tape simultaneously in one device. As an example, if you install 8 heads and the tape is 180'+
FIG. 11 shows an example of the arrangement of a rotary head in a digital recording/reproducing device that distributes signals to four systems by winding α.

In FIG. 11, heads 28 to 2H mounted on the circumference of the rotating drum 1 at equal intervals and at the same height sequentially come into contact with and leave the magnetic tape 3 as the rotating drum 1 rotates. Since more than one are in contact at the same time,
Four types of signals can be recorded or played back. Therefore, a track pattern as shown in FIG. 12 is formed on the magnetic tape 3 with a track pitch T that is approximately proportional to the feed speed. At this time, for each adjacent head, +
Azimuth angles A" and -A" are set, and high recording density can be obtained by eliminating guard bands by so-called azimuth overwriting.

[Problems to be Solved by the Invention] In the arrangement of the rotary head described with reference to FIGS. 11 and 12, there is a demand for changing the bit rate of digital signals that can be recorded and reproduced. In other words, by reducing the amount of information using techniques such as band compression,
There is a demand for longer recording and playback times at the cost of a slight deterioration in image quality.

Therefore, in the conventional example described above, the following three methods can be considered to accomplish this.

(1) Change only the tape speed.

(2) Change the tape speed and the number of rotations of the rotating drum proportionally.

(3) Change the tape speed and the number of heads used proportionally.

However, all of these methods have significant drawbacks. The reason for this will be explained when the bit rate is 172 times, that is, the recording time is doubled.

In the first method, as shown in FIG. 13, the track pitch increases by 172 times, and the signal S/N ratio deteriorates by about 3 dB. This method is generally used in analog recording devices, but it has a serious effect on digital signal recording because it increases the data error rate.

In the second method, the track pitch does not change, but the rotation speed of the rotary drum 1 is reduced to 1/2, which causes mechanical difficulties such as increased rotational unevenness and worsened head touch. Furthermore, since the signal frequency handled by the head is reduced to 1/2, there arises an electrical problem in that it is not possible to optimize the transmission system such as a reproduction amplifier or equalizer.

In the third method, two systems are recorded in parallel using heads 2^, 2C, 2E, and 2G (see Figure 14), but four heads with the same azimuth are used, resulting in crosstalk. . Furthermore, if other heads are used, the track pitch will not be constant, which is inconvenient.

Therefore, in view of the above points, an object of the present invention is to record with the same track pitch regardless of changes in tape speed.
An object of the present invention is to provide a rotary head device configured to realize reproduction.

[Means for Solving the Problems] The present invention provides a rotary head type recording or reproducing device that simultaneously records or reproduces signals of a plurality of systems, which includes 2N heads having a first azimuth and a second azimuth. N heads having a third azimuth, and N heads having a third azimuth, the head having the second azimuth and the third azimuth.
The trace loci of the azimuth heads are arranged alternately on the recording medium at uniform intervals, and the trace loci of the first azimuth head are arranged between the trace loci of the second and third azimuth heads. Each head is arranged as follows.

[Function] In the present invention, 2N first azimuth heads (A),
N second azimuth heads (B) and N third azimuth heads (II:) ^, B, A, C, A, B.
By arranging them on the rotating drum in the order of
At the tape feed speed of 2. Since recording or reproduction is performed using only the third azimuth rotating head, azimuth recording with the same track pitch can be performed at any tape feed speed.

[Example] Hereinafter, the present invention will be described in detail based on examples.

First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

Figures 1 and 2 are diagrams showing the arrangement of the rotating head of a digital video tape recorder (DVTR) according to an embodiment of the present invention. Figure 1 is a diagram showing the arrangement on a drum, and Figure 2 is a side development view. be. In both of these figures, Hel to He4 are heads at the first azimuth (01), Bl and B2 are heads at the second azimuth (+α0), and CI and C2 are heads at the third azimuth (-α°). , which are arranged on the rotating drum 1 at equal intervals in the order shown. Moreover, the height of each of these heads in the direction of the rotation axis is also adjusted to be the same. Further, 3 is an In magnetic tape, which is wound around the rotating drum 1 over an angular range of 180°+α.

In this configuration, a total of 8 heads are used to feed the magnetic tape 3 at a speed of v while rotating the rotary drum 1 at a predetermined number of rotations, and 4 of the 8 heads are in contact with the magnetic tape 3 at the same time. By sequentially selecting four heads and recording four systems of signals, the track pattern shown in FIG. 3 is obtained.

That is, if the azimuth of adjacent tracks is 00. +α0
,0″.

-α0', and guard panless high-density recording can be realized.

Next, set the tape speed to 172 VT and set the four heads to 8.
1, B2. By sequentially selecting two of CI and C2 that are in contact with the tape at the same time and recording two systems of signals, the track pattern shown in FIG. 4 is obtained. That is, the azimuths of adjacent tracks are +α°, -α°, etc., and the track pitch is almost the same as in the case of tape speed v7 described above, only the number of signal systems has been reduced from 4 to 2. in,
Both the S/N and frequency of the recorded and reproduced signals do not change.

5 to 8 are diagrams for explaining a DVTR according to a second embodiment of the present invention.

FIG. 5 and FIG. 6 are diagrams showing the head configuration of this embodiment, and are a diagram showing the arrangement on the drum and a side development view, respectively, and each symbol in the diagram is a diagram showing the head configuration of the first embodiment described above. Similar to the example. In this embodiment, each head AI and B
l, A2 and CI, A3 and 84. 84 and C2 are arranged close to each other with a phase difference of 90°. However, head A1. A2. A3. A4 to the same height, and heads Bl, f12. CI and C2 are set at the same height with a step X between them.

The magnetic tape 3 is wound around the drum at an angle of 270°+α, and six or more of the eight heads are always in contact with the magnetic tape 3, so that six systems of simultaneous recording are performed at the tape speed Vt. In this way, the track pattern shown in FIG. 7 is obtained.

Next, the tape speed is set to 1/2 VT, and the heads Bl and B
If only 2° CI and C2 are used and three systems are simultaneously recorded, the track pattern shown in FIG. 8 is obtained.

That is, the track pitch is the same as in the case of tape speed vy in FIG. 7.

FIG. 9 is a block diagram showing the head switching section according to the first embodiment, and FIG. 1O shows the switching signals SW^ to SWD and mode signals SP/
It is a timing chart of LP (short play/long play) and R/P (recording/playback).

As shown in FIG. 9, the input signal is A/D converted by an A/D converter 20, and then encoded, an error correction code is added,
The modulation unit 22 performs processing such as DC component suppression modulation. Then, 4 lines or 2 lines are provided corresponding to the mode signal SP/LP.
The signals are converted into parallel signals of the system and further supplied to each head.

The timing is determined by the switching signal 5III generated based on the phase of the rotating drum, as shown in FIG.
It is determined by A to SWD.

The above is the operation during recording, and during playback, a mode detection section (not shown) determines the mode of the recorded signal, and outputs from each head in accordance with the mode signals SP/LP generated thereby. The output signal is obtained by demodulating and multiplying by D.

It should be noted that the present invention can be carried out regardless of the winding angle of the tape.Furthermore, the second and third azimuth beds are alternately arranged on the same top of the rotating drum at equal intervals and at the same height. Sometimes, the first azimuth heads may be non-equally spaced at positions between these.

Furthermore, if the number of heads is a multiple of 4, then 12, 1
The present invention can be similarly applied even if there are six or the like.

As in the embodiments described with reference to FIGS. 1 to 8,
The first azimuth is 0°, the second and third azimuths are each +α0. For example, the first azimuth may be set to +α°, the second azimuth to 0°, and the third azimuth to -α°, or completely separate C0 and β
°, γ°, etc. may be used.

[Effects of the Invention] As explained above, the present invention has a configuration using 2N first azimuth heads, N second azimuth heads, and N third azimuth heads. Therefore, high-density recording or reproduction can be performed with the same track pitch and the same relative speed even in a mode where the tape speed is twice as different.

[Brief explanation of the drawing]

1 is a diagram showing the arrangement of the head of a DVTR on a drum as a first embodiment of the present invention; FIG. 2 is a side development view showing the height relationship and azimuth of the DVTR head of FIG. 1; Figures 3 and 4 each have a tape speed of 7 teeth. Figures 5 to 8 are diagrams showing the head arrangement on the drum of the DVTH of the second embodiment, a side development view, and a tape speed of v7 and 1/2 VT. FIG. 9 is a block diagram showing the head switching section according to the first embodiment of the present invention, FIG. 1θ is a waveform diagram showing the operation of FIG. 9, and FIG. 11 is a diagram of a conventional DVTR. A diagram showing an example of head arrangement, and FIGS. 12 to 14 are track pattern diagrams of a conventional DVTR, respectively. 1... Rotating drum, 3... Tape, Al~^4... First azimuth head, 81, B
2...Second azimuth head, CI, C2...
3rd azimuth head, vH: rotational speed of the rotating drum, ■T: tape speed, X: head installation step. Figure 2 τVT Figure 4 Figure 6 ΣVT Figure 8 TI Figure VT Figure 12 VT Figure 14

Claims (1)

[Claims] 1) A rotary head type recording or reproducing device that simultaneously records or reproduces signals of a plurality of systems, comprising 2N heads having a first azimuth and N heads having a second azimuth.
and N heads each having a third azimuth, the trace trajectories of the head having the second azimuth and the head having the third azimuth being alternately arranged at uniform intervals on the recording medium. and a rotary head type recording characterized in that the heads are arranged so that the trace locus of the first azimuth head is arranged between the trace loci of the second and third azimuth heads. playback device. 2) The rotary head type recording or reproducing apparatus according to claim 1, wherein the first, second, and third azimuth rotary heads are disposed on the same surface. 3) The second and third azimuth rotating heads are arranged on the same plane, and the first azimuth rotating head is arranged with a predetermined step difference therebetween. The rotating head type recording or reproducing device according to item 1.