JPH0551981B2 - - 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 apparatus suitable for application to, for example, a rotary head type video tape recorder, a PCM tape recorder, etc., in which a block is configured for each digital information signal of a predetermined length, and a block address signal is assigned to each block. When recording a predetermined number of blocks, a recording signal is supplied every other scan, and when the rotary head is used to form a recording track, and when reproducing the digital information signal, the rotational speed of the rotary head is adjusted to the same speed as when recording. A memory is provided in which the digital information signals reproduced by the rotary head are written in accordance with the reproduced block address signals for each scan, and the digital information signals written in this memory are read out in the same order as when they were recorded. This allows the digital signal to be in the same time sequence as when it was recorded, thereby making it possible to reproduce the digital information signal without performing highly accurate tracking.

[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, etc. are factors that hinder the low cost of rotary head type recording and reproducing devices.

The object of the present invention is to realize a rotary head type recording/reproducing apparatus that eliminates the need for a high-precision machined high-hardness cylinder, a high-precision servo, etc. required for tracking. Furthermore, the present invention focuses on the fact that, unlike analog information signals, even when digital information signals are made continuous, the seams do not become discontinuous, and it is an object of the present invention to provide a rotary head type recording and reproducing device for reproducing digital information signals. It is something to do.

[Means to solve the problem]

The rotary head type recording/reproducing apparatus of the present invention has, for example, a first
As shown in the figure, a block is constructed for each digital information signal of a predetermined length, a block address signal is added to each block, and when recording a predetermined number of blocks,
A recording signal is supplied every other scan, and when reproducing a digital information signal, the rotary head 2 is supplied with a recording signal to form a recording track. A memory 18 into which the digital information signal reproduced is written in accordance with the reproduced block address signal.
By reading out the digital information signals written in the memory 18 in the same order as in the recording, the digital information signals are in the same time series as in the recording.

[Effect]

According to the present invention, the reproducing scan of the rotary head 2 is performed twice on a recording track in which a predetermined number of block diagrams to which address signals have been added are recorded, and the reproduced digital signals are reproduced. Data is written in the memory 18 in accordance with the block address signal, and the digital signals written in the memory 18 are read out in the same order as when they were recorded, so that they can be reproduced without performing highly accurate tracking.

[Embodiment] An embodiment of the rotary head type recording/reproducing apparatus of the present invention will be described below with reference to the drawings. This example is an example applied to a rotating head type PCM tape recorder.

In FIG. 2, 1a and 1b indicate an upper drum and a lower drum, respectively, for guiding the magnetic tape, and a rotating head 2 slightly protrudes from between these two drums.
A magnetic tape 3 running while being wound obliquely over 360 degrees on both sides of drums 1a and 1b is brought into sliding contact with a rotary head 2. As shown in FIG. 3, inclined recording tracks T _o-1 , T _o , T _o+1 , . . . are sequentially formed on the magnetic tape 3 . In this example, the recording tracks T _o-1 , T _o , T _o+1 ,
The track width Wt of ... is selected to be equal to the guard band width Wg between adjacent tracks.

In FIG. 1, an analog signal to be recorded, such as an audio signal, is supplied to an input terminal indicated by 4,
The A/D converter 5 converts the signal into an audio PCM signal. This audio PCM signal is supplied to the encoder 6, where a synchronization signal, error correction code, and error detection code are added. FIG. 4 shows the code structure of recording data obtained from the output of the encoder 6. 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 audio PCM signals or error correction codes. 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 TBC as described below.
This is used to individually distinguish 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 the encoder 6 is supplied to a modulator 7 and converted into a code format suitable for recording and reproduction.
Various modulation methods such as NRZI, 3PM, MFM, etc. can be used. A recording signal obtained from the output of the modulator 7 is supplied to the rotary head 2 via an amplifier 8, a recording terminal 10r of a recording/reproducing switch 9, and a rotary transformer (not shown). In this case, in this example, a recording signal is supplied to the rotary head 2 every other scan of the rotary head 2.

During reproduction, the number of rotations of the rotary head 2 is the same as during recording, so that a reproduction operation is performed every time the magnetic tape 3 is scanned. That is, the rotary head 2 scans the magnetic tape 3 twice while the magnetic tape 3 is fed by one recording track. In this way, the number of scans during playback is doubled compared to the number of scans during recording, so the playback scanning trajectory pitch is smaller than the recording track pitch, and even without tracking,
One or more playback scanning trajectories will necessarily pass through each of all recording tracks.

The playback output of the rotary head 2 is taken out to the playback side terminal 10p of the recording/playback switch 9, and is sent to the playback amplifier 11.
is supplied to the detector 12 via. The detector 12 shapes the waveform of the reproduced signal into a pulse signal. The output of this detector 12 is supplied to a clock extraction circuit 13, and a clock pulse synchronized with the reproduced data is extracted. The output of this clock extraction circuit 13 is supplied to a demodulation circuit 14, and reproduced data having the same code structure as the recorded data is obtained.

This reproduced data is supplied to a delay circuit 15, a synchronous separation circuit 16, and a CRC checker 17. CRC
The checker 17 uses a synchronization signal to detect the presence or absence of errors in each block of reproduced data and block address signals using a CRC code.
An error flag indicating the presence or absence of an error is generated for each block in the output. The air flag becomes "1" when an error is detected, and becomes "0" when no error is detected. The delay circuit 15 delays the reproduced data and block address signal by the time required for error detection by the CRC checker 17.

The above-mentioned playback data, block address signal, and error flag are processed by the time base collector (hereinafter referred to as
(abbreviated as TBC) 18. TBC18
consists of a memory (RAM) and its peripheral circuits.Basically, the reproduced data is written to the memory by a clock synchronized with the reproduced data, and the memory is written by a reference clock from the timing generation circuit 19. It is configured to read data from and remove time axis fluctuations. Writing to the memory of the TBC 18 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. When there is an error, writing is prohibited to prevent writing to the wrong address. be done. 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 of the memory of the TBC 18 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 20.

The decoder 20 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, the average value of correct data located before and after. Output data from this decoder 20 is supplied to a D/A converter 21, and a reproduced audio signal is taken out at an output terminal 22.

In one embodiment of the invention described above, the track width Wt
and the guard band width Wg are equal, and the number of scans during playback is twice the number of scans during recording, so the recording tracks T _o-1 , T _o , T _o+1 and the playback scan trajectory N ₁ , N ₂ , N ₃ , N ₄ , and N ₅ are shown in Figure 5A.
It will be as shown below. When the rotary head 2 first scans in the direction of the arrow, a scanning locus _N1 passing through the recording tracks T _o-1 and T _o is drawn, and the reproduced signal shown in FIG. 5B is
S ₁ is obtained. The reproduced signal has an envelope approximately proportional to the area of the region where the recording track and the scanning locus overlap. Below, the second scanning trajectory N ₂ ,
Every time the third scanning trajectory N ₃ and the fourth scanning trajectory N ₄ are drawn, reproduction signals S ₂ , S ₃ , and S ₄ are generated in sequence. Focusing on the recording track _T0 , the reproduction output from this recording track _T0 is as shown by the solid line in FIG. 5B. The envelopes of the reproduced signals S ₁ and S ₃ reach their maximum values at the timings of t ₂ and t ₄ , and the envelopes of the reproduced signals S ₂ and S ₄ reach their maximum values at the timings of t ₁ and t ₃ . Such a playback signal
S ₁ to _{S 4} are supplied to the above-mentioned reproduction system and processed, but when the level of the reproduction signals S ₁ to _{S 4} falls below a predetermined value, for example, 1/3 of the maximum value, the S/N deteriorates. , the waveform may not be shaped correctly by the detector 12. Therefore, the reproduced signals S ₁ to S ₄ and the corresponding reproduced data DT ₁ to _{DT 4} have invalid data sections (indicated by cross marks) intermittently, as shown in FIG. 5C. . However, regarding the recorded track T _o of interest, the data obtained in the interval t ₃ to _{t 4} in the reproduced signal S ₁ and the interval t ₃ to t ₄ in the reproduced signal S ₂ are the same. Similarly, data obtained in the interval t ₂ to _{t 3} in the reproduced signal S ₂ and the interval t 2 to t 3 in the reproduced signal S ₃ , and the interval _{t 1 to t 2 in} the reproduced signal S ₃ and t ₁ to _{t 2} in the playback signal S ₄
Each of the data obtained in the interval is the same. Due to this duplication of playback data, even if the playback data includes an invalid data section, the data in that part will be played back in the next scan, so there will be no problem. . In addition, in FIG. 5C, the shaded area indicates the recording track.
It shows the interval where the same data is obtained overlappingly among the data of T _o . Of course, the recording track T _o
The reproduction data of other recording tracks is also the same as described above.

In this way, while the original audio PCM signal or the audio PCM signal whose arrangement has been regularly changed by interleaving is recorded on one recording track, the time series of the reproduced data is This will be different from when it was recorded. However, when writing playback data to the memory of the TBC 18 as described above, writing is performed at the address determined by the block address signal added to each block of playback data, and reading is performed using the addresses in the same order as when recording. Since this is done by specifying TBC
The time series of output data No. 18 is the same as that at the time of recording.

In addition, in the above-mentioned embodiment, the head width during playback is
Although Wh is assumed to be equal to the track width Wt of the recording track, the relationship (Wh>Wt) may also be established. For example, when (Wh = 1.5Wt), Fig. 6 A
Reproduction signals S ₁ to S ₄ as shown in FIG.
Corresponding playback data DT ₁ to _{DT 4} as shown in Figure B
are obtained sequentially. Furthermore, when (Wh=2Wt), reproduced signals S ₁ to _{S 4} as shown in FIG. 7 are sequentially obtained.

As is clear from these figures 6 and 7, by setting (Wh > Wt), the S/
N can be made better. On the other hand, since crosstalk occurs because two or more recording tracks are scanned at the same time, it is necessary to take countermeasures against crosstalk.

As can be understood from the above explanation, according to this example, there is no need for tracking in which the head scans one-to-one with the recording track, so there is no need to perform high-precision tracking servo, and the mechanical Freed from precision. 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 the magnetic tape on the guide drum, it is not necessary to apply lateral pressure to the magnetic tape to regulate the position of the tape edge on one side, so that the sliding contact between the rotary 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, making it possible to manufacture a rotary head type recording/reproducing device easily and inexpensively.

It goes without saying that the present invention can be applied to recording and reproducing digital information signals such as digital video signals and measurement data in addition to digital audio signals.

〔Effect of the invention〕

According to the present invention, there is an advantage that digital signals recorded at high density can be reproduced without performing high-precision tracking.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the rotary head type recording/reproducing apparatus of the present invention, FIGS. 2 and 3 are schematic diagrams showing the mechanical configuration and recording pattern of one embodiment of the present invention, and FIG. The figure is a schematic diagram showing the structure of recorded data, FIG. 5 is a schematic diagram and time chart used to explain the operation of an embodiment of the present invention, and FIGS.
The figures are time charts used to explain other embodiments of the present invention. 1a and 1b are tape guide drums, 2 is a rotary head, 3 is a magnetic tape, 18 is TBC, T _{o -1} , T _o ,
T _o+1 is a recording track, and N ₁ to _{N 3} are reproduction scanning trajectories.

Claims (1)

[Claims] 1 A block is constructed for each digital information signal of a predetermined length, a block address signal is added to each block, and when recording a predetermined number of blocks, a recording signal is supplied every other scan, and a block is provided for forming a recording track. A rotary head, and a memory in which the rotational speed of the rotary head when reproducing a digital information signal is approximately the same as that during recording, and the digital information signal reproduced every scan by the rotary head is written in accordance with the reproduced block address signal. 1. A rotary head type recording and reproducing apparatus, characterized in that the digital information signals written in the memory are read out in the order in which they were recorded, so that the same time series as in the recording is obtained.