JPH02270108A - Rotary head type recording/reproducing device - Google Patents

Abstract

PURPOSE:To excellently record and reproduce signals without using a tracking servo by alternately supplying recording signals to first and third rotary heads every other scanning operation when the first and third rotary heads scan tracks, and alternately fetching reproduced signals from first and second rotary heads every other scanning operations from the first and second rotary heads when the first and second rotary heads scan the tracks at the time of reproducing. CONSTITUTION:First and second rotary heads HA and HB' having different azimuth angles, and a third rotary head HB, which is provided at the almost same rotating angle position as the first rotary head HA and possesses the same azimuth angle as the second rotary head HB, are provided. A recording/reproducing circuit, which alternately supplys recording signals to the first and third rotary heads HA and HB every other scanning operation when the first and third rotary heads HA and HB scan the track at the time of recording, and alternately fetch the reproduced signals every other scanning operation from the first and second rotary heads HA and HB' when the first and second rotary heads HA and HB' scan the track at the time of reproducing, is provided. Thus the signals can be excellently recorded, and they can be reproduced without using the highly accurate tracking servo.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary head type recording and reproducing device suitable for application to, for example, a rotary head type video tape recorder, a PCM tape recorder, and the like.

[Summary of the invention]

The present invention relates to a rotary head type recording and reproducing device suitable for application to, for example, a rotary head type video tape recorder, PCM tape recorder, etc. In a rotary head type recording/reproducing device in which two recording tracks are formed so as to be sequentially and alternately arranged on the tape-shaped recording medium, the two recording tracks are arranged opposite to each other at positions separated from each other by a predetermined rotational interval, and each first and second rotating heads having different azimuth angles; and a third rotating head disposed at substantially the same rotational angular position as the first rotating head and having the same azimuth angle as the second rotating head. , during recording, in the scanning of the first and third rotating heads, l
A recording signal is alternately supplied to the first and third rotary heads every scan, and during reproduction, the first and second rotary heads are alternately supplied to the first and second rotary heads for each scan.
By including a recording and reproducing circuit that takes in reproduction signals from the rotary head, it is possible to perform good recording and reproduction without applying tracking servo during recording and reproduction.

[Prior Art and Problems to be Solved by the Invention] A VTR (video tape recorder) is well known as a rotary head type recording/reproducing device.The rotary head device of a conventional VTR is constructed as shown in FIG. In FIG. 9, (2) shows the tape guide drum, and the magnetic tape (1) is held on the tape guide drum (2), for example, by 180°.
HA and H8 represent rotating magnetic heads arranged so as to run obliquely over an angular range of , and HA and H8 are arranged such that their angular intervals differ from each other by 180 degrees, and the azimuth angle of the two equally rotating magnetic heads H7 and H6 is (The inclination angle of the gap with respect to the direction perpendicular to the scanning direction) is made to be different from each other.

In a conventional rotary head type recording/reproducing apparatus using such a rotary head device, a video signal for each field is alternately supplied to the rotary magnetic heads HA and Hll, and this video signal is transmitted by the rotary magnetic heads HA and H3. Recorded on magnetic tape (1). In this case, as shown in FIG. 10, video signal tracks Ta and Tg are formed adjacent to each other obliquely with respect to the width direction of the magnetic tape (1), and these tracks T and T have different azimuths. The so-called inclined azimuth recording is performed by the rotating magnetic heads Ha and H3, respectively. If the tracks TA and T are formed adjacent to each other by performing inclined azimuth recording in this way, even if a track shift occurs during reproduction, signals from adjacent tracks can be recorded by rotating magnetic heads Ha and Hm with different azimuths. Therefore, the amount of pickup (crosstalk) of signals from adjacent tracks to be scanned due to track deviation can be suppressed to a small level. Therefore, it is possible to arrange the tracks adjacent to each other and record at high density without providing a guard band between the tracks.

However, in the conventional rotary head type recording/reproducing device constructed in this manner, if the rotating side race surface of the bearing that rotatably supports the rotating shaft on which the rotating magnetic heads HA and H8 are integrally mounted is tilted, the bearing will cause waviness. ,
The rotating magnetic heads HA and Hll, which are integrally attached to the rotating shaft, rotate while vibrating in different vertical directions. Therefore, although adjacent tracks should originally be formed parallel to each other on the magnetic tape (1) as shown in FIG. 10, the adjacent tracks TA and T1 become meandering curves that are different from each other as shown in FIG. The track widths of TA and Tm fluctuate, and when this fluctuation becomes large, track missing occurs.Therefore, a magnetic tape (1) in which the track width fluctuates and track missing occurs in this way.
When reproducing the data, the output level of the reproduced signal decreases, resulting in a decrease in the S/N ratio.

In addition, in such a conventional rotary head type recording/reproducing device, during reproduction, a control signal recorded in the longitudinal direction of the side edge of the magnetic tape (1) is reproduced together with a recording signal, and this control source signal is used to control the rotary magnetic head Ha. , Hm and the capstan, and control the scanning trajectory of the rotating magnetic head Ha,' Hg and the recording tracks Ta, T during reproduction
Tracking servo is applied so that el matches.

In addition, high-grade VTRs do not rely solely on control signals.
This rotating magnetic head HA has a configuration in which the rotating magnetic heads H, , H, are movable by piezoelectric elements.

The rotating magnetic heads HA and H1 are moved by changes in the envelope of the reproduced signal obtained by wobbling H3, or by crosstalk components of pilot signals having different frequencies between several recording tracks, so as to perform correct tracking. I have to. Further, in order to carry out proper tracking, it is necessary that the tape running path including the tape guide drum has high mechanical precision and that the tape guide drum has high hardness. A tracking servo with a high precision of the second order, high precision of work, etc. had disadvantages that hindered the development of low-coast rotary head type recording and reproducing devices.

In view of the above, an object of the present invention is to propose a rotary head type recording and reproducing apparatus that can perform good reproduction without requiring high-precision tracking servo and can always perform good recording.

[Means to solve the problem]

The rotary head type recording/reproducing apparatus of the present invention scans the rotary head obliquely with respect to the tape-shaped recording medium (1) as shown in FIGS. 1 and 2, thereby recording the first and second recording tracks TA and Tm. In a rotary head type recording/reproducing device configured to sequentially and alternately arrange the following on the tape-shaped recording medium (1), the recording and reproducing devices are arranged opposite to each other at positions separated from each other by a predetermined rotational interval, and different First and second rotary heads HA and H1' having azimuth angles, arranged at approximately the same rotational angular position as this first rotary head HA, and having the same azimuth angle as this second rotary head H1l'. During recording, a recording signal is supplied to the third rotary head H8 and alternately to the first and third rotary heads HA and H3 every l scan during scanning of the first and third rotary heads HA and H1. At the same time, during playback, the first and second rotary heads HA are alternately scanned for each scan during scanning by the first and second rotary heads HA, H, and J.
and a recording/reproducing circuit that takes in reproduction signals from H and r.

[Effect]

According to the present invention, during the scanning of the first and third rotary heads H0 and Hl, which are arranged at approximately the same rotational angular position during recording, the first and third rotary heads are rotated alternately every other scan. Since recording is performed by supplying recording signals to Second rotating head H
In scanning a and HB', this first
Since the reproduction signals from the second rotary heads HA and HII' are taken in, reproduction can be performed without applying high-precision tracking servo.

〔Example〕

Hereinafter, one embodiment of the rotary head type recording/reproducing apparatus of the present invention will be described with reference to the drawings.

This example is an example applied to a rotating head type PCM tape recorder.

FIG. 2 shows the rotary head device in this example. In FIG. 2, (2) indicates a tape guide drum, and its size is, for example, 30 mm to 40 mm in diameter.

A magnetic tape (1) is run diagonally along this tape guide drum (2) over an angular range of, for example, 180°. Further, HA, H, and H, / are rotating magnetic heads, respectively. The magnetic heads HA and Hm are used during recording, and are mounted with a sufficiently small angular interval θ1, for example 1°, with respect to the rotational direction X, with the magnetic head HA leading. Further, the azimuth angles (the inclination angles of the caps with respect to the direction perpendicular to the scanning direction) of the magnetic heads Ha and Hm are made different from each other. Further, the scanning trajectories of the magnetic heads HA and H8 on the magnetic tape (1) are made to coincide with each other. For example, the magnetic head θ is lower than the magnetic head in the direction of the rotation axis. Furthermore, the magnetic heads HA and H3' are used during reproduction, and are
In this example, θ is set to be 180°, which is attached with an angular interval θ2. The azimuth angle of the magnetic head H' is made the same as the azimuth angle of the magnetic head H3. Further, the magnetic heads HA and l(, / are arranged so that the scanning trajectory on the magnetic tape (1) is shifted by (N+-)) rack pitches (N is an integer), that is, the recording track pitch is set to TP, The corresponding angular spacing of the magnetic head is θ.

In this case, the magnetic heads Ha and H1l' are mounted along the axis of rotation. In this example, N=-1, θ, =
At 360°, θ,=180@, and is shifted by T,=0. Further, the magnetic heads HA+Hm and H1' are rotated in the X direction at, for example, 60 rotations/second while maintaining the above-mentioned positional relationship.

During recording, each time the magnetic heads HA and H3 rotate once and scan the magnetic tape (1), the recording signal S RtC is sequentially and alternately supplied, and the recording signal S RtC is supplied to the magnetic head H1l. At this time, the erasing signal SELASE is supplied to the magnetic head Ha.

In Fig. 1, the input terminal (3) has an analog signal,
For example, an audio signal is supplied, this audio signal is converted into an audio PCM signal by an AD converter (4), and this is supplied to an encoder (5).

This encoder (5) adds a synchronizing signal, an error correction code, an error detection code, and compresses the time axis. FIG. 3 shows the code structure of recording data obtained at the output of the encoder (5). A synchronization signal, a block address signal, and a CRC code for error detection are added to data consisting of a plurality of samples of an audio PCM signal or an error correction code. As the error correction code, a parity code, an adjacent code, etc. can be used, and interleaving may also be used. The block address signal is for distinguishing individual blocks in a series of playback data input to the memory of the TBC (time base collector) as described later, and is a simple incremental code signal.
A combination of multiple types of addresses can be used.

The CRC code is designed to detect the presence or absence of errors in both the block address signal and data. The output of this encoder (5) is then supplied to a modulator (6) and modulated using a modulation method such as NRZI, 3PM, or MFM. On the output side of this modulator (6), as shown in FIG. 4A, there is a recording signal S□ corresponding to the 180'' range that the magnetic heads HA and Hg scan on the magnetic tape (1). , is obtained. This recording signal S REe is supplied to the B side terminal of the changeover switch (7) and the A side terminal of the changeover switch (8). Also, (9) is the erasing signal S!
This is an oscillator that generates LAS, for example, the recording signal S□
. A signal with a frequency more than twice the highest frequency of is the erasing signal S! Generated as LAI. This erasing signal S
The level of ELASE is, for example, 1.2 to 3 times the level of recording signal 5IIEC. This erasing signal S ELA
SE is supplied to the A side terminal of the changeover switch (7). The B side terminal of the changeover switch (8) is grounded. A switching control signal Sc as shown in FIG. 4B is supplied to the changeover switches (7) and (8).
and (8) are switched in conjunction. That is, the control signal S
, are respectively switched to the A side when they are at a high level "1", and are respectively switched to the B side when the control signal S is at a constant level "0".

As shown in the fourth diagram, only the recording signal S□ is obtained from the changeover switch (8), and this is sent to the recording amplifier (10),
The signal is supplied to the magnetic head H3 through the recording side terminal R of the recording/reproducing switch (11) and a rotary transformer (not shown). Further, as shown in FIG. 4C, a recording signal stie and an erasing signal S! are transmitted from the changeover switch (7). LA0 is obtained alternately and supplied to the magnetic head HA through the recording amplifier (12), the recording side terminal of the recording/reproducing switch (13), and a rotary transformer (not shown). The erasing signal S! from this changeover switch (7)! LA3E is obtained at the same timing as the recording signal S□ obtained from the changeover switch (8).

In this way, during recording, the recording signal S1lte is sequentially and alternately supplied to the magnetic heads HA and H8 for each angular range of 180° to scan the magnetic tape (1), so that the recording signals S1lte are sequentially and alternately supplied to the magnetic heads HA and H8 to scan the magnetic tape (1). As shown in FIG. 5, recording tracks TA and TI are sequentially formed by magnetic heads HA and H6. In this case, the scanning trajectory of the magnetic head H1 is made the same as that of the magnetic head HA, and when the recording signal S□0 is supplied to the magnetic head Hm, the scanning trajectory of the magnetic head H1 is made the same as that of the magnetic head HA.
A is the erasing signal S! :LA! ! is supplied, so
Before recording track T is formed by magnetic head H3, for example, previously formed recording track T0 is erased by magnetic head HA. Further, in this case, since the magnetic heads HA and Hm are arranged at almost the same rotational angle position, the recording tracks by the magnetic heads HA and Ha can be recorded even if there is center runout of the rotation axes of the magnetic heads Ha and Hil. Since the vibrations are the same, the recording tracks TA and Ts have a constant width as shown in FIG.

Also, during reproduction, the magnetic heads HA and H8 are
' is scanned with a shift of one track pitch (-TP) as described above. In this example, the magnetic heads HA and HB' are installed with an angular spacing of 180°, so the magnetic heads HA and H1' output reproduction signals every 1806 angular ranges as shown in FIGS. 7A and B. S□ is obtained.

The reproduction signal 5PII from the magnetic head HA is sent to the detector (15) through a rotary transformer (not shown), the reproduction side terminal P of the recording/reproduction switch (13), and the reproduction amplifier (14A).
A). The detector (15A) is the reproduced signal S
This waveform shapes the PI into a pulse signal.

The output of this detector (15A) is the clock extraction circuit (
16A), and a clock pulse synchronized with the reproduced data is extracted. The output of this clock extraction circuit (164) is supplied to the demodulation circuit (17A), and reproduced data having the same code structure as the recorded data is obtained.

This playback data is transferred to the delay circuit (18A) and the synchronization separation circuit (
19A) and a CRC checker (2OA).

The CRC checker (204) uses a synchronization signal to detect the presence or absence of an error in each block of playback data and block address signals using a CRC code, and outputs an error flag indicating the presence or absence of an error in each block. is generated and supplied to the TBC (21). The error flag is, for example, "1" when an error is detected, and becomes 0° when no error is detected. The delay circuit (18A) operates only for the time required for error detection by this CRC checker (20A).
Delay playback data and block address signals. This delayed playback data and block address signal are TBC
(21).

Further, the reproduction signal SPI from the magnetic heads H, + is supplied to the detector (15B') through a rotary transformer (not shown), the reproduction side terminal P of the recording/reproduction switch (22), and the reproduction amplifier (14B'). Detector (15B')
Clock extraction circuit (16B'), demodulation circuit (17B')
, delay circuit (1BB'), synchronous separation circuit (19B'),
The CRC checker (2OB') is the detector (1
5A), clock extraction circuit (16A), demodulation circuit (17
A), delay circuit (18A), synchronous separation circuit (19A),
It is configured similarly to the CRC checker (2OA). Therefore, an error flag is generated in the CRC checker (20B'), which is supplied to the TBC (21). Also,
The reproduced data and block address signal delayed by the delay circuit (18B') are supplied to the TBC (21).

The TBC (21) is composed of a memory (RAM) and its peripheral circuits, and basically writes the reproduced data using a clock that is synchronized with the reproduced data, and writes the reproduced data using a reference clock from the timing generation circuit (23). It is configured to read data from memory and remove time axis fluctuations. Writing to the memory of TBC (21) is performed using addresses based on the block address signal, and writing of data determined to have an error by the error flag is prohibited. As mentioned above, the error flag indicates not only the data but also the presence or absence of an error in the block address signal, so if there is an error, writing is prohibited to prevent writing to the wrong address. be made into

Also, if writing is prohibited, previously written data remains at the corresponding address, so in order to prevent this from being read as correct data, it is necessary to ensure that the data at that address is error data. Writes an error flag indicating. This error flag is written immediately after correct data is read. Reading of the memory of TBC (21) is performed sequentially in a predetermined order,
The output is a data series and an error flag indicating the presence or absence of an error for each block.
4).

The decoder (24) corrects data determined to have errors using an error correction code, and performs correction by replacing uncorrectable data with interpolated data. The interpolated data is, for example, the average value of correct data located before and after. Output data from this decoder (24) is supplied to a D/A converter (25), and an audio signal is taken out at an output terminal (26).

In this example described above, during playback, the magnetic heads HA and H11' that obtain the playback signal 5PII are configured to perform magnetic checking, so that the error rate during playback is averaged, and the S/P of the playback audio signal is It is possible to prevent N from significantly deteriorating locally. That is, with respect to the recording track pattern on the magnetic tape (1), the magnetic head H
When A and H3' are in the relationship as shown in FIG. 8A, the magnetic head Ha scans the recording track TA accurately, so that the reproduced signal 5P reproduced from the recording track TA is
II has a good error rate. On the other hand,
Since the magnetic head H8' scans the middle of the recording tracks TA and T, the level of the reproduction signal SPI reproduced from the recording track T8 decreases, and the error rate worsens. However, the sum of these error rates does not deteriorate so much, and the S/N of the reproduced audio signal does not deteriorate so much. Similarly, when the relationship is as shown in FIG. 7B, the S/N of the reproduced audio signal does not deteriorate significantly.

Similarly, when there is a relationship as shown in Figure 8,
The S/N of the reproduced audio signal does not deteriorate so much. Therefore, according to this example, the error rate during reproduction is averaged even without applying tracking servo, and it is possible to prevent the S/N of the reproduced audio signal from being significantly degraded locally.

Note that in the above embodiment, the track pitch T.

Although an example has been described in which the angular interval θa corresponding to . In this case, the mounting position of the above-mentioned (N+-+ magnetic head may be determined).Furthermore, according to the above-mentioned embodiment, only one of the magnetic heads is used for both recording and reproducing. Two pieces can also be used.

〔Effect of the invention〕

As described above, according to the present invention, good reproduction can be performed without applying tracking servo, and rotational unevenness can be caused by rotating heads HA, H! Even if there is positive fluctuation, there is an advantage that recording tracks of a constant width can be formed alternately.

[Brief explanation of drawings]

゛ Fig. 1 is a block diagram showing an embodiment of the rotary head type recording/reproducing device of the present invention, Fig. 2 is a block diagram showing an example of the rotary head device, and Figs. 3 to 8 are lines for explaining the same. Figure, No. 9
The figure is a configuration diagram showing an example of a conventional rotary head device, and FIGS. 10 and 11 are diagrams for explaining the conventional technique. (1) is a magnetic tape, (2) is a tape guide drum, (7
) and (8) are changeover switches, (11) and (13) respectively.
) and (22) are the recording/reproduction switches, respectively, and (21) is the TBC.
1 (23) is a timing generation circuit, (26) is an output terminal, and HA, H, and H8' are rotating magnetic heads, respectively.

Claims (1)

[Scope of Claims] A rotating device in which first and second recording tracks are sequentially and alternately arranged on the tape-shaped recording medium by scanning a rotary head obliquely with respect to the tape-shaped recording medium. In a head-type recording/reproducing device, first and second rotating heads are arranged opposite to each other at positions separated from each other by a predetermined rotational interval, and each has a different azimuth angle; a third rotary head disposed at a rotational angular position and having the same azimuth angle as the second rotary head; and during recording, the first and third rotary heads alternately rotate the azimuth angle every other scan; A recording signal is supplied to the first and third rotary heads, and during reproduction, the reproduction signals from the first and second rotary heads are taken in alternately for each scan of the first and second rotary heads. A rotary head type recording and reproducing device comprising: a recording and reproducing circuit;