JPS62243112A - Tracking control device - Google Patents

Abstract

PURPOSE:To obtain a tracking error signal in all positions of an inclined recording track on a magnetic tape by providing a rotary head, a position control means, a detecting circuit, and a tracking error detecting circuit, and executing a control, based on a square-law detection output of a reproducing output. CONSTITUTION:A digital signal is reproduced by a rotary head 7 from an inclined recording track on a magnetic tape 1 which has recorded the digital signal to which a data rearrangement processing has been performed, by which a reproducing signal having no correlation to a signal reproduced from an adjacent track is obtained, and by bringing a reproducing output by the rotary head 7 to square-law detection, a detecting output corresponding to a tracking error is obtained, and by forming a tracking error signal from this detecting output, a tracking control of the rotary head is executed. In this way, the tracking error signal is formed in all positions of the inclined recording track on the magnetic tape, and the tracking control can be executed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tracking control device applied to a digital video tape recorder or the like that records and reproduces digital signals, and particularly relates to a tracking control device that is applied to a digital video tape recorder or the like that records and reproduces digital signals, and in particular, the present invention relates to a tracking control device that is applied to a digital video tape recorder or the like that records and reproduces digital signals. The present invention relates to a tracking control device that performs tracking control by controlling the position of a rotary head in the width direction of a track.

[Summary of the invention]

The present invention provides a trunking control device that performs tracking control by controlling the position of a rotary head in the width direction of an inclined recording track formed on a magnetic tape, in which data is rearranged into digital signals to be recorded on the recording track. By performing the processing, the correlation between signals reproduced from adjacent tracks by the rotary head is eliminated, and trunking control can be performed based on the square law detection output of the reproduced output by the rotary head.

[Conventional technology]

In general, helical scan magnetic recording and reproducing devices such as video tape recorders that use a rotating head to record video signals record signals on an inclined recording track on the magnetic tape that is traced by the rotating head during recording, and then reproduce the signals. Sometimes, reproduction is performed by tracing a tilted recording track on which a signal has been recorded using the rotary head.

In addition, in a helical scan type magnetic recording/reproducing device, in order to prevent S/N deterioration of the reproduced signal due to crosstalk components from the indirect tilt recording track, each tilt on the magnetic tape 51 is set as shown in FIG. A guard band recording method in which a no-signal area (so-called guard band) 53 is provided between recording tracks 52, or a guard band recording method in which a no-signal area (so-called guard band) 53 is provided between recording tracks 52, and a recording azimuth of each adjacent inclined recording track 56, 57 on a magnetic tape 55 as shown in FIG. A recording method that changes the azimuth is used.

In addition, in a helical scan type magnetic recording/reproducing device, as disclosed in Japanese Patent Application Laid-Open No. 57-135583, a rotating head is attached to an electro-mechanical transducer such as a bimorph plate, and the rotating head is perpendicular to the scanning direction. 3. A so-called bimorph head whose position is controlled in the width direction of the magnetic tape is used to correct the tracking error, that is, the deviation between the tilted recording track on the magnetic tape and the reproduction scanning locus during the playback operation, and performs tilt recording using the rotary head. It is known that a tracking control device is provided to accurately trace a track. Conventionally, the tracking error has been obtained by, for example, sampling the pedestal portion of the reproduced signal every horizontal scanning period (IH) and comparing it with a reference signal level.

Furthermore, in a digital video tape recorder that records and plays back digital signals, the digitized signal requires about 10 times more bandwidth than the original analog signal, so the same amount of information as an analog video recorder can be recorded on a magnetic tape. For recording, it is necessary to reduce both the recording wavelength and track pitch. In addition, in the case of digital recording,
The S/N can be reduced by 20 to 30 dB compared to analog recording, and the recording wavelength and track pitch can be reduced within this range. If the guard band recording method or azimuth recording method is adopted, during variable speed playback operation in which the scanning locus of the rotating head spans multiple inclined recording tracks, there will be many parts where no playback signal can be obtained, and the amount of playback information will be reduced. It is known that there is a shortage of ko and hi.

[Problem that the invention seeks to solve]

By the way, as mentioned above, the pedestal part of the reproduced signal is
Conventional tracking control l which controls the bimorph head by obtaining a tracking error signal by sampling every horizontal scanning period (IH) and comparing it with a reference signal level. The tracking required when a conventional tracking control device is applied to a digital video tape recorder, in which highly accurate tracking control cannot be performed because the signal cannot be obtained; therefore, both the recording wavelength and track pitch must be made small. Accuracy was extremely difficult to obtain.

In view of the above-mentioned problems, the present invention provides a novel configuration that enables highly accurate tracking control by making it possible to obtain tracking error signals for all positions of inclined recording tracks on a magnetic tape. The object of the present invention is to provide a tracking control device.

[Means for solving problems]

In order to achieve the above-mentioned object, a tracking control device according to the present invention includes: a rotary head for reproducing digital signals from an inclined recording track on a magnetic tape on which digital signals subjected to data rearrangement processing are recorded; A position control means for controlling the position of the rotary head in the track width direction, a detection circuit for square-law detection of the reproduced output from the rotary head, and a tracking error detection circuit for detecting a tracking error from the detection output from the detection circuit. It is characterized in that tracking control is performed based on the square law detection output of the reproduced output from the head.

[Effect]

In the tracking control device according to the present invention, a rotary head reproduces the digital signal from an inclined recording track on a magnetic tape in which a digital signal subjected to data rearrangement processing is recorded, thereby producing a signal reproduced from an adjacent track. By performing square law detection on the reproduction output from the rotary head, a detection output corresponding to the tracking error is obtained, and a tracking error signal is formed from this detection output to perform tracking of the rotary head. Take control.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a tracking control device according to the present invention will be described in detail below with reference to the drawings.

In the block diagram of FIG. 1 showing the configuration of an embodiment of a digital video tape recorder to which the present invention is applied, a magnetic tape 1 is spirally wound around the outer periphery of a rotary head drum 2 over an angular range of approximately 360°. , a capstan 4 driven by a capstan motor 3 and a pinch roller 5 are configured to run at a predetermined speed. Further, the rotary head drum 2 is configured to be rotated at a constant speed by a drum motor (not shown).

The rotary head drum 2 is provided with a video head 7 that is cantilevered by a bimorph plate 6 made of two pieces of piezoceramic material bonded together. The bimorph board 6 is
In the recording operation mode, the video head 7 is fixed at a predetermined height position, and in the playback operation ff mode, the video head 7 is moved so that a tracking servo system 30, which will be described later, accurately traces a target track on the magnetic tape l. is displaced in the track width direction. Further, a strain gauge 8 such as a resistance wire strain gauge is attached to the surface of the bimorph plate 6 to detect the amount of deflection of the bimorph plate 6, that is, the amount of displacement of the video head 7 in the track width direction.

The video controller 7 is selectively connected to a recording processing system 1O and a reproduction processing system 20 via a switch circuit 9.

The recording processing system 10 includes a 7° analog-to-digital (A/D) conversion circuit 12 that digitizes the analog video signal supplied to the signal input terminal 11, and the A/D conversion circuit 1.
2, a scramble processing circuit 13 rearranges the data of the digital video signal obtained in step 2, and the scrambled digital video data is sent to the video head 7 via the switch circuit 9 as a recording signal.
It is composed of a recording amplifier 14 and the like.

In this embodiment, in the recording operation mode, the video head 7 sequentially runs over each inclined recording track TR on the magnetic chip 11 without providing a guard band between the tracks as shown in FIG. From the recording processing system 10 to the above switch circuit! Non-azimuth recording is performed on each of the inclined recording tracks TR using the recording signal supplied via J.

Here, the scrambling circuit 1 of the recording processing system IO
3 performs a data rearrangement process on the recording signals, that is, the digital video data recorded in a non-azimuth manner on each inclined recording track TR on the magnetic tape 1 so that there is no correlation between adjacent tracks.

The playback processing system 20 also includes a playback amplifier 21 that amplifies the playback output from the video head 7, and a device that performs data rearrangement processing corresponding to the data rearrangement processing performed by the scrambling processing circuit 13 of the recording processing system 10 described above. - Consists of a scramble processing circuit 13, a digital/analog (D/A) conversion circuit 23, etc., which converts the reproduced digital video signal obtained by the descramble processing circuit 13 into an analog signal and outputs it from the signal output terminal 24. ing.

In this embodiment, the playback processing system 20 is configured to track each inclined recording track TR of the magnetic tape l on which digital video data subjected to data rearrangement processing as described above is recorded.
Digital video data obtained as a playback output by tracing with the video head 7 is supplied via the switch circuit 9 in the playback operation mode, and the playback output, that is, the digital data is scrambled by the recording processing system 10. The descrambling processing circuit 13 performs a data sorting process corresponding to the data sorting process performed by the processing circuit 13, thereby restoring the order of the digital video data to the D/A conversion circuit 2.
3, the reproduced analog video signal is reproduced and output from the signal output terminal 24.

Furthermore, in this embodiment, in the playback operation mode, the playback output obtained in step 7 to the video is transmitted to the playback processing system 2.
The signal is amplified by the regenerative amplifier 21 of 0 and supplied to the square law detection circuit 31 and address data generation circuit 34 of the tracking servo system 30.

The square law detection circuit 31 of the tracking servo system 30 is as follows:
The detected output is supplied to a multiplier 33 via a low pass filter (LPF) 32. Further, the multiplier 33 has
A signal detecting the amount of displacement of the video head 7 is supplied from a strain gauge 8 provided on the bimorph plate 6. Then, the multiplier 33 is connected to the LPF 32.
The square-law detection output signal supplied via the strain gauge 8 is multiplied by the displacement detection signal supplied from the strain gauge 8, and the multiplication output is supplied to the first adder 34.

Further, the address data generation circuit 34 of the tracking servo system 30 forms address data of the digital video data obtained as the playback output from the video head 7 in the playback operation mode, and sends clock pulses of the data to the tape speed detection circuit 35. In addition to supplying
The synchronization pulse of the digital video data is supplied to the reproduction phase detection circuit 37. The tape speed detection circuit 35 detects the tape speed of the magnetic tape I from the period of the supplied clock pulse, and supplies the detection output to a ramp voltage generator 36 and a jump determination circuit 39. The gradient voltage generator 3G adds a gradient voltage for displacing the rad 7 to the video according to the tape speed of the magnetic tape 1 indicated by the detection output of the tape speed detection circuit 35. It is supplied to the container 41. Further, the reproduction phase detection circuit 37 compares the phases of the phase reference signal Vref supplied to the reference signal input terminal 38 and the synchronization pulse supplied from the address data generation circuit 34, thereby determining the reproduction phase of the digital video data. is detected, and the detection output is sent to the jump determination circuit 39.
is supplied to. Furthermore, the jump determination circuit 39 detects the tape speed of the magnetic tape l indicated by the detection output of the tape speed detection circuit 35 and the tape speed indicated by the detection output of the reproduction phase detection circuit 37 in the variable speed playback operation mode. Jump data is supplied to the jump voltage generator 40 at predetermined timing according to the reproduction phase of digital video data.

The jump voltage generator 40 supplies the first adder 41 with a jump voltage according to the jump data.

Further, the first adder 41 adds the multiplication output of the multiplication Z:33 to the ramp voltage and jump voltage, and sends the added output to the second adder 43 via the integrator 42.
is supplied to. The second adder 43 is supplied with a sine wave excitation signal (a so-called wobbling signal) having a frequency of, for example, 720 II z from an oscillator 44, and is given to this wobbling signal as the integral output of the integrator 42. The tracking control signals are added together and the output thereof is supplied to the bimorph plate 6 as a drive signal.

In the embodiment configured as described above, in the reproduction operation mode, the video head 7 tracks two adjacent inclined recording tracks TRX, TR on the magnetic tape 1, for example, as shown by broken lines in FIG. When scanning is performed across the recording track TRX, the video controller 7 outputs a reproduction output (X) at a reproduction level corresponding to the width X that is in sliding contact with one of the inclined recording tracks TRX, and a reproduction output ( Reproduction output (Y) at a reproduction level corresponding to the width y in sliding contact with the recording track TRy
A reproduction output (X+Y) is obtained by adding the above.

In the tracking servo system 30 to which the reproduced output (X+Y) is supplied, the square-law detection circuit 31 generates a square-law detected output (X+y) of the reproduced output (X + Y).
)z, and convert this square law detection output (X+y)z to the above Lr.
By averaging in F32, a signal Sig is obtained as shown in the first equation: Sig=((X+Y)")=((Xt+pxy+Y").

Note that ρ is a correlation coefficient between the respective reproduction outputs (X) and (Y). Moreover, [...] indicates averaging.

In this embodiment, data rearrangement processing is performed by the scrambling circuit 13 of the recording processing system 10 as described above, and the magnetic tape! Each inclined recording track T”H on the
Since the recording signal recorded on the digital video data (F') is designed so that there is no correlation between adjacent tracks, the correlation coefficient ρ of each reproduction output (X), (Y) is
is abbreviated as O.

Therefore, the output signal Sig of the LPF 3' 2 is expressed by the second formula Sig = (X'') + (Y''), and the output signal Sig of the LPF 3' 2 is expressed by the second equation, and the output signal Sig of the LPF 3' Book tilt recording track TRx
, each reproduction output (X) obtained from TRy.

This is a signal indicating the sum of each envelope of (Y).

Therefore, by setting the amount of tracking error to a<l, the first
Rewriting the formula, Sig = (((1-a) X+aYl!)-
((1-a)”X”+2a (1-a)pXY+a”Y”)=(1
-a)” (X”)+a’ (Y”).

That is, the output signal Sig of the LPF 32 draws a curve with a minimum value of a=0.5 with respect to the amount of tracking error.

In this embodiment, the bimorph plate 6 is excited by the wobbling signal output from the oscillator 44, and the reproduced output obtained by the video head 7 includes an AM component due to the wobbling signal. The tracking error is detected by multiplying the displacement detection signal corresponding to the wobbling signal by the strain gauge 8 provided on the bimorph plate 6 and the output signal Sig of the LPF 32 in the multiplier 33 to perform so-called synchronous detection. This tracking error signal is passed through the integrator 42 to the second signal adder 4.
3, tracking error is corrected. The tracking error signal formed based on the square law detection output of the reproduction output can be traced over the entire range of each inclined recording track TR on the magnetic tape 1, and can be traced to all positions of each inclined recording track TH. Highly accurate tracking control can be performed for

In addition, in the variable speed reproduction operation mode in which the magnetic tape 1 is run at a tape speed different from the tape speed in the recording operation mode and the reproduction operation is performed, one When tracing a track repeatedly or skipping over several tracks, for example, when playing at 2.25x speed, the scanning trajectory of the video hendro will be as shown by the dashed line in Figure 4. TR,,TR,,TR,
... has a tilt error of 1.25 pinch, and it is necessary to correct this tilt error, and to correct the decimal (0,25) of the track pitch ratio, 5 traces are required. It is necessary to increase the playback track pinch every time. Therefore, in this embodiment, the ramp voltage generator 36 applies a ramp voltage that displaces the video head 6 by 1.25 pitches during the scanning period of one track, and the jump voltage generator 40 provides a jump every five traces. A voltage is applied to drive the bimorph plate 6 with a drive voltage as shown in FIG. 5, so that 2.25 times speed reproduction is performed.

〔Effect of the invention〕

As is clear from the description of the embodiments described above, in the tracking control device according to the present invention, the digital signals are sent to the rotary head from the inclined recording track on the magnetic tape on which the digital signals subjected to the data rearrangement processing are recorded. By reproducing the signal from the adjacent track, a reproduced signal that has no correlation with the signal reproduced from the adjacent track is obtained, and by performing square law detection on the reproduced output from the rotary head, a detection output corresponding to the tracking error is obtained, and from this detection output. Since tracking control of the rotary head is performed by forming a tracking error signal, tracking error signals can be formed for all positions of the inclined recording track on the magnetic tape and tracking control can be performed with high precision.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a digital video recorder to which the present invention is applied, and FIG. 2 is a schematic diagram showing inclined recording tracks on a magnetic tape used to explain the operation of this embodiment. 1, and FIG. 3 is a schematic diagram showing the trace state when performing a 2.25 times speed increase operation in the above embodiment, and FIG. 4 is a waveform diagram showing the driving voltage supplied to the bimorph board. It is. FIGS. 5 and 6 are schematic diagrams showing recording formants according to the conventionally known guard band recording method and azimuth recording method. l... Magnetic tape 2... Rotating head drum 6... Bimorph plate 7... Video head 8... Strain gauge 9... Switch circuit 10... Recording processing system 11... Signal input Terminal 12...A/D conversion circuit 13...Scrambling processing circuit 20...Reproduction processing system 22...Descramble processing circuit 23...D/A conversion circuit 30...Tracking servo system 31 ... Square law detection circuit 32 ... LPF 33 ... Multiplication circuit. 41.43... Adder 42... Integrator 44... Oscillator

Claims (1)

[Scope of Claims] A rotary head for reproducing digital signals from an inclined recording track on a magnetic tape on which digital signals subjected to data rearrangement processing are recorded; and a position control for controlling the position of the rotary head in the track width direction. means, a detection circuit for square law detection of the reproduced output from the rotary head, and a tracking error detection circuit for detecting a tracking error from the detection output by the detection circuit, and tracking based on the square law detection output of the reproduction output from the rotary head. A tracking control device characterized in that it performs control.