JPH0554163B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary head type recording and reproducing apparatus 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/reproducing device suitable for application to, for example, a rotary head type video tape recorder, PCM tape recorder, etc., in which a block is configured for each digital information signal of a predetermined length, and an address signal is added to each block. When recording a predetermined number of blocks, a recording signal is supplied every other rotation, and recording tracks with different azimuth angles are alternately formed, and this digital information signal is transmitted to a recording rotary head having a different azimuth angle. When reproducing, the rotation speed of the reproducing rotary head having an azimuth angle corresponding to the azimuth angle of the recording rotary head is set to be approximately the same as during recording, and the digital information signal reproduced for each scan is reproduced by the reproducing rotary head. By providing a memory that is written in accordance with the address signal and making it continuous by reading out the digital information signals written in this memory in a predetermined order, high-density recording is possible during recording and when playing back. This makes it possible to reproduce data without using a high-precision tracking servo.

[Problems to be solved by conventional technology and invention]

A VTR (video tape recorder) is well known as a rotary head type recording and reproducing device. Traditional
For high-density recording, VTRs have track widths of several tens of micrometers or less, and control signals recorded along the longitudinal edge of the magnetic tape are reproduced along with recording signals, and the magnetic tape is rotated by this control signal. The rotation of the head and capstan is controlled, and a tracking servo is applied so that the scanning locus of the head during reproduction matches the recording track. In addition, in high-end VTRs, the rotary head is configured to be movable not only by control signals but also by a piezoelectric element, and changes in the envelope of the reproduced signal obtained by wobbling the rotary head, or changes between several recording tracks. Due to the crosstalk components of the pilot signals that have different frequencies,
The rotating head is moved to ensure correct tracking.

Further, as a prerequisite for performing regular 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.

These high-precision tracking servos, high machining precision, and the like are obstacles to lowering the cost of rotary head type recording/reproducing devices.

The present invention provides high-precision machining required for tracking,
The purpose of this invention is to realize a rotary head type recording/reproducing device that does not require any high-hardness cylinders, high-precision servos, etc.

[Means to solve the problem]

The rotating head type recording/reproducing apparatus of the present invention configures a block for each digital information signal of a predetermined length as shown in FIG. 1, and an address signal is added to each block. A recording signal is supplied every other time, and recording tracks T _A and T _B of different azimuth angles are alternately formed.
Recording rotary heads H _A and H _B each having a different azimuth angle, and a reproducing rotary head having an azimuth angle corresponding to the azimuth angle of the recording rotary heads H _A and H _B when reproducing this digital information signal.
The rotational speeds of H _A and H _B ′ are almost the same as during recording,
A memory 21 is provided in which the digital information signal reproduced every scan by the reproduction rotary heads H _A and H _B ' is written in accordance with the reproduced address signal. The data are made continuous by reading them in order.

[Effect]

According to the present invention, when recording a predetermined number of blocks, a recording signal is supplied every other rotation to the recording rotary heads H _A and H _B having different azimuth angles to record the predetermined number of blocks at different azimuth angles. Recording is performed alternately to form recording tracks T _A and T _B , and when reproducing, for these recording tracks T _A and T _B ,
The reproduction rotary heads H _A and H _B ', which have azimuth angles corresponding to the azimuth angles of the recording rotary heads H _A and H _B , are rotated at approximately the same number of rotations as during recording to reproduce the reproduced digital information signal. is written in the memory 21 according to the reproduced address signal, and the digital information signals written in the memory 21 are read out in a predetermined order, so that 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 this Figure 2, 2 indicates a tape guide drum, and its size is, for example, 30 mm to 30 mm in diameter.
It is 40mm. A magnetic tape 1 is run diagonally along this tape guide drum 2 over an angular range of, for example, 180°. Further, H _A , H _B and H _B ' are each rotating magnetic heads. Magnetic head H _A and
H _B is used during recording and is mounted with a sufficiently small angular spacing θ ₁ , for example 1°, with respect to the rotational direction x, and in such a way that it is preceded by the magnetic head H _A . Further, the azimuth angles (the inclination angles of the caps with respect to the direction perpendicular to the scanning direction) of the magnetic heads H _A and H _B are made to be different from each other. Further, the scanning trajectories of the magnetic heads H _A and H _B on the magnetic tape 1 are made to coincide with each other. For example, the magnetic head H _A is lowered by one track pitch x θ ₁ /360° than the magnetic head H _B in the direction of the rotation axis. In addition, magnetic heads H _A and H _B ′ are used during reproduction, and the rotation direction x
It is attached with an angular spacing θ ₂ relative to the In this example, θ ₂ =180°. The azimuth angle of the magnetic head H _B ' is made the same as that of the magnetic head H _B . Moreover, these magnetic heads H _A and H _B ′ are
The scanning locus on the magnetic tape 1 is shifted by (N+1/2) track pitches (N is an integer). That is, when the recording track pitch is T _P and the angular interval θ _T between the magnetic heads with respect to this, the magnetic heads H _A and H _B ' are (N+
It can be installed with an offset of 1/2 + θ ₂ /θ _T ) × T _P.
In this example, N=-1, θ _T =360°, and θ ₂ =180°
, it is installed with a shift of T _P = 0, and 1/2
The track pitch (1/2T _P ) is shifted. Further, the magnetic heads H _A , H _B and H _B ' are rotated in the x direction at, for example, 60 revolutions/second while maintaining the above-mentioned positional relationship.

During recording, each time the magnetic heads H _A and H _B rotate once and scan the magnetic tape 1, a recording signal S _REC is generated.
are sequentially and alternately supplied, and the magnetic head H _B
When the recording signal S _REC is supplied to the magnetic head,
An erasing signal S _ELASE is supplied to H _A.

In FIG. 1, an analog signal, for example an audio signal, is supplied to an input terminal 3, and this audio signal is converted into an audio signal by an A-D converter 4.
A PCM signal is supplied to the encoder 5. In this encoder 5, a synchronization signal,
Addition of an error correction code and error detection code, and compression of the time axis are performed. FIG. 3 shows the code structure of recording data obtained from the output of the encoder 5. Multi-sample audio PCM
A synchronization signal, a block address signal, and a CRC code for error detection are added to data consisting of a 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 the TBC (time base collector) as described below.
This is for individually distinguishing blocks in a series of reproduced data input to the memory, and a simple incremental code signal, a combination of multiple types of addresses, etc. 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, where it is modulated using a modulation method such as NRZI, 3PM, or MFM. On the output side of this modulator 6, magnetic heads H _A and H _B are connected to the magnetic tape 1 as shown in FIG. 4A.
A recording signal S _REC is obtained corresponding to the 180° range scanned above. This recording signal _SREC is supplied to the B side terminal of the changeover switch 7 and the A side terminal of the changeover switch 8. In addition, 9 is a signal for erasing
This is an oscillator that generates S _ELASE , for example, a recording signal.
A signal with a frequency that is more than twice the highest frequency of S _REC is generated as the erasing signal S _ELASE . The level of the erasing signal _SELASE is, for example, 1.2 to 3 times the level of the recording signal _SREC . This erasing signal S _ELASE 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 S _C as shown in FIG. 4B is supplied to the switching switches 7 and 8, and these switching switches 7 and 8 are switched in conjunction. That is, when the control signal S _C is at a high level "1", they are switched to the A side, and when the control signal S _C is at a low level "0", they are switched to the B side.

From the changeover switch 8, only the recording signal _SREC is obtained as shown in FIG. 4D, and this is sent to the recording amplifier 1.
0, the magnetic head is connected through the recording side terminal R of the recording/reproducing switch 11 and a rotary transformer (not shown).
Supplied to H _B. Further, the recording signal S _REC and the erasing signal S _ELASE are alternately obtained from the changeover switch 7 as shown in FIG.
2. The magnetic head is connected to the recording side terminal R of the recording/reproducing switch 13 and the rotary transformer (not shown).
Supplied to H _A. The erasing signal S _ELASE from the changeover switch 7 is obtained at the same timing as the recording signal S _REC obtained from the changeover switch 8 .

In this way, during recording, the recording signal S _REC is sequentially and alternately supplied to the magnetic heads H _A and H _B for each angular range of 180° that scans the magnetic tape 1 . As shown in Figure 5, the magnetic head
Recording tracks T _A and T _B are sequentially formed by H _A and H _B. In this case, the scanning locus of the magnetic head H _B is made the same as that of the magnetic head H _A , and when the recording signal S _REC is supplied to the magnetic head H _B , the erasing signal S _ELASE is supplied to the magnetic head H _A.
is supplied, so that before the recording track T _B is formed by the magnetic head H _B , the previously formed recording track _TO is erased by the magnetic head H _A.

When reproducing a magnetic tape 1 on which recording tracks T _A and T _B are formed alternately, magnetic heads H _A and
As described above, H _B ' scans with a deviation of 1/2 track pitch (1/2 T _P ). Magnetic head H _A and
Since H _B ' are installed with an angular spacing of 180° in this example, these magnetic heads H _A and
From H _B ', reproduced signals S _PB are obtained for each angular range of 180° as shown in FIGS. 6A and 6B.

The reproduction signal _SPB from the magnetic head H _A is supplied to the detector 15A through a rotary transformer (not shown), the reproduction side terminal P of the recording/reproduction switch 13, and the reproduction amplifier 14A. The detector 15A shapes the waveform of the reproduced signal _SPB into a pulse signal.
The output of this detector 15A is supplied to a clock extraction circuit 16A, and a clock pulse synchronized with the reproduced data is extracted. This clock extraction circuit 1
The output of 6A is supplied to the demodulation circuit 17A, and reproduced data having the same code structure as the recorded data is obtained.

This reproduced data is supplied to a delay circuit 18A, a synchronous separation circuit 19A, and a CRC checker 20A.
The CRC checker 20A uses a synchronization signal to detect the presence or absence of an error in each block of reproduced 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 this is
Supplied to TBC21. The error flag is, for example, "1" when an error is detected, and "0" when no error is detected. The delay circuit 18A delays the reproduced data and block address signal by the time required for error detection by the CRC checker 20A. This delayed reproduction data and block address signal are supplied to the TBC 21.

In addition, the reproduction signal S _PB from the magnetic head H _B ' is transferred to a rotary transformer (not shown) and a recording/playback switch 2.
The signal is supplied to the detector 15B' through the reproduction side terminal P of No. 2 and the reproduction amplifier 14B'. Detector 1
5B', clock extraction circuit 16B', demodulation circuit 17
B', delay circuit 18B', synchronous separation circuit 19B',
CRC Checker 20B' is the detector 15 mentioned above.
A, clock extraction circuit 16A, demodulation circuit 17A,
The configuration is similar to the delay circuit 18A, synchronous separation circuit 19A, and CRC checker 20A. Therefore,
An error flag is generated by the CRC checker 20B' and is supplied to the TBC 21. In addition, reproduced data and block address signals 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 reproduced data using a clock synchronized with the reproduced data, and reads data from the memory from the timing generation circuit 23 using a reference clock. It is configured to read out and remove time axis fluctuations. this
Writing to the memory of the TBC 21 is performed using an address based on a 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 when there is an error, writing is prohibited to prevent writing to the wrong address. Ru. In addition, if writing is prohibited, previously written data remains in 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 reading correct data. Reading from the memory of the TBC 21 is performed sequentially in a predetermined order, and a data series and an error flag indicating the presence or absence of an error for each block are obtained as output and supplied to the decoder 24.

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

In this example described above, during playback, the playback signal
Since the magnetic heads H _A and H _B ' that obtain S _PB scan the magnetic tape 1 with a deviation of 1/2 track pitch (1/2 T _P ), the error rate during playback is averaged. , it is possible to prevent the S/N of the reproduced audio signal from being significantly degraded locally. That is, when the magnetic heads H _A and H _B ' have a relationship as shown in FIG. 7A with respect to the recording track pattern on the magnetic tape 1, the magnetic head H _A accurately scans the recording track T _A. , the playback signal _SPB played from the recording track _TA
The error rate is good. On the other hand, the magnetic head H _B ' scans the middle of the recording tracks T _A and T _B ;
The level of the reproduced signal _SPB reproduced from _TB 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 so much. Therefore, according to this example, the error rate during reproduction is averaged, and it is possible to prevent the S/N of the reproduced audio signal from being significantly degraded locally.

Therefore, according to the present invention, there is no need for tracking in which the head scans one-on-one with the recording track, so there is no need to perform high-precision tracking servo, and the need for mechanical precision is eliminated. In other words, firstly, it is not necessary to specify the phase relationship between the recording track and the reproduction scanning trajectory, so a high-precision phase servo is not required.Secondly, the inclination of the recording track and the reproduction scanning trajectory Thirdly, since the recording track or playback scanning trajectory can meander, the precision of the tape path may be low.Fourthly, the tape path does not need to be accurate because the When winding magnetic tape around a guide drum, there is no need to apply lateral pressure to the magnetic tape to restrict one tape edge on one side.
The sliding contact between the rotating head and the magnetic tape can be made stable. For these reasons, it is also possible to form the tape guide drum from molded plastic, and the rotary head type recording/reproducing device can be manufactured easily and inexpensively.

〔Effect of the invention〕

As described above, according to the present invention, there is an advantage that high-density recording is possible during recording, and good reproduction is possible without applying high-precision tracking servo during reproduction.

[Brief explanation of the drawing]

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 7 are diagrams for explaining the same. It is. 1 is a magnetic tape, 2 is a tape guide drum, 21
is TBC, 23 is a timing generation circuit, 26 is an output terminal, and H _A , H _B and H _B ' are rotating magnetic heads, respectively.

Claims (1)

[Claims] 1 A block is constructed for each digital information signal of a predetermined length, an address signal is added to each block, and when recording a predetermined number of blocks, a recording signal is supplied every other rotation, and each recording track with a different azimuth angle is recorded. When reproducing the digital information signal, the rotational speed of the recording rotary heads, which are formed alternately and each having a different azimuth angle, and the reproducing rotary head, which has an azimuth angle corresponding to the azimuth angle of the recording rotary head, is approximately the same as that during recording. and a memory in which the digital information signal reproduced by the reproduction rotary head for each scan is written in accordance with the reproduced address signal, and the digital information signal written in the memory is read out in a predetermined order. A rotary head type recording and reproducing device characterized in that the recording and reproducing device is made continuous.