CA1111961A

CA1111961A - Method and apparatus for correcting tracking errors of a transducer which scans parallel record tracks

Info

Publication number: CA1111961A
Application number: CA286,258A
Authority: CA
Inventors: Masahiro Kambara; Yukio Kubota; Hidehiko Okada; Minoru Morio
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1976-09-09
Filing date: 1977-09-07
Publication date: 1981-11-03
Also published as: DE2740770A1; NL7709919A; FR2364580A1; DE2740770C2; ATA647477A; AT380365B; GB1582486A; FR2364580B1; JPS5333109A

Abstract

ABSTRACT OF THE DISCLOSURE
A method and apparatus for correcting tracking errors of a transducer which scans successive, parallel, adjacent record tracks of n record medium so as to reproduce information signals therefrom. The information signals, which may comprise video signals, are recorded in the parallel record tracks, and pre-determined signals also are recorded at predetermined locations in the information signals. When the information and predeter-mined signals are played back, at least one cross-talk predeter-mined signal which is recorded in at least one adjacent track also is played back. The cross-talk predetermined signal is detected and a control signal is produced response to the level of the detected cross-talk predetermined signal. The position of the transducer with respect to the track being scanned thereby is adjusted in accordance with the control signal. In one embodiment, the control signal is recorded at a predetermined location in each horizontal blanking interval of the video signals; and the horizontal blanking intervals which are recorded in one track are displaced with respect to the horizontal blanking intervals which are recorded in the adjacent track. This displacement of the horizontal blanking intervals, and thus the predetermined signals, in adjacent tracks facilitates the detection of the cross-talk predetermined signals which, for example, may comprise pilot signals.

-i-

Description

BACKGROUND OF THE INVENTION
This invention re].ates to a method and apparatus for correcting tracking errors in a transducer which scans successive, parallel tracks of a record medium and, more partic-llarly, to such a rnlthod and apparatus wherein the position of the transducer rela-tive to the track being scanned can be adjusted when a tracking error condition is sensed.
Signal recording and/~r reproducing apparatus are known wherein a rotary head assembly scans successive parallel tracks on a record medium so as to record signal.information by scanning the record medium with the rotary head or heaas. The record medium generally used in such apparatus is magnetic tape, magnetic sheets, magnetic discs and various other types of media. In additi.on to rotating the head or heads across the record medium, the medium also is moved. One particular use o such apparatus is to record video signal inEormation on, for example, mac3rletic tape, wherein parallel slant tracks are recorded in skewed relation to the longitudinal axis of the tape. In addition to video si~nal informa-tion, such apparatus is capable of recordinq other types of analog signals or, if desired, digital signals representing various types of information. In the interest of simplification, the following explanation and description refers to video signal recorders which use magnetic tape, such as the video tape recorder (VTRl However, it should be understood that this explanation and description also is applicable to different types of recordi.ng apparatus ~such. as other types of analog or digital recorders) which use different media.
A typical VTR includes one, and preferably twc, record/
playback heads mounted on a suitable rotary assembiy so as to rotatably scan a magnetic tape which is helically wrappe~ about .
... . , ~11961 at least a portion of a guide drum. During recording, a tracking servo system synchronizes the movement of the tape to the rotary movement of the heads, and control signals wh;ch can be used for thi.s type of synchronism during a reproducing operation are recorded on the tape. ~lence, during reproduction, this same servo control system is used to synchronize the movement of the tape to the rota-tion of the heads. Consequently, a generally accurate video picture can be displayed in response to t~e reproduced video sLgnals. That is, this servo control system is operative to control the relative movement between the rotary heads and the tape such that each head scans substantially the same track during reproduction as was scanned during recording. :
However, even with this servo control system, there are instances wherein ~he path traversed by the heacls during reproduc-lS tion does not coincide satisfactorily with the recorded record track. This is particularly true when the video signals are recorded by one VTR and are reproduced Erom the tape.by a different VTR. If the orbits of the magnetic heads in these di.fferent ~TRIs are not equal to each other, the servo control system may not be effective to bring the heads into coincidence with the recorded ~ tracks during reproduction. Other factors also may be present which prevent successful operation of the servo control system.
Consequently, the scanning magnetic heads may exhibit tracking errors during reproduction.
The tracking errors mention.ed above may not be partic-: ularly noticeable or objectionable for VTR apparatus wherein parallel tracks are recorded with guard bands separati.ng adjacent track.s ...
or when the magnetic tape is transported at a sufficiently higher speed. However, the problems caused by these tracking errors ~2-. .

~ . . . . . . . .
- . . : : - . -during signal reproduction may not be acceptable if the guard bands between adjacent tracks are reduced and if the speed at ~, which the magnetic tape is transported is reduced. The desirable effect of eliminating the guard bands, and thus increasing the recordi,ng density (tracks per inch), and oE reducing the transport speed of the magnetic tape is to increase the amount of video signal information which can be recorded on a magnetic tape of - given lengths. This, in turn, increases the recording capacity (generally expressed as a measure of time) of the VTR without requiring a concommitant increase in the supply or length of recording tape. In particular, for these so-called "longer-playing" VTR's, tracking errors may reduce the signa]-to-noise ratio and may otherwise deleteriously affect the reproducing characteristics.
OBJ~CTS OF THE XNVENTIO~
Therefore, it is an o~jec-t of the present invention to provide an improved method and apparatus for correcting tracking errors which may occur in rotary head recording/reproducing apparatus Another object of this invention is to provide a method and apparatus for correcting tracking errors in a rotary head recording/reproducing system so as to correct for deviations between the scanning path of a head and a record track on the record medium.
A further object of this invention is to provide a method and apparatus for correcting tracking errors in a rotary head recording/reproducing system wherein the scanning path of the rotary head is adjusted so as to coincide with a previously recorded track.

, . ' .. ' ' .' ,' ' , . ' ' , ' 6~

An addi-tional object of this invention is to provide a method and apparatus for correcting tracking errors of a scanning head which tra.verses a scanning path that may deviate from a desired path, this deviation being corrected by di.splacing the support member upon wh.ich the head is mounted durincJ the scanning operation.
Yet another object of this invention is to correct for tracking errors which may occur in a video signal reproducing device wherein a playback head may deviate from a record track on a record medium having parallel, adjacent record tracks.
A still further object of this invention is to provide a method and apparatus for controlling the scanning of a record track by a scanning head during a reproducing operation so as to avoid deleterious effects upon the reproduced siynals.
Another object of this invention is to provide a method and apparatus for recording particular signal.s on a record medium in a video signal recorder, which signals .3re de-tected and used during a reproducing operation to correct ~or tracking errors of the reproducing transducers in, for exam~l~, a long-playi.ng vi.deo recorder.
Various other objects, advantages and features of the present invention will become readily apparent from the ensuing . .
detailed description, and the novel features will be parti.cularly pointed out in the appended claims.
SUMMARY OF THE INVF.NTION
In accordance with the present invention, predetermined signals are recorded in successive traclcs of a record ~edium such that when these predetermined signals are reproduced, as by a rotary transducer, tracking errors of that transducer may be easily correcte such that the transducer accurately scans a record track. The record ,', .,'.. , ' ' ".', . '' '.,''. .`, ,' '' ' ' ".""' ' ' ' ''"' ' ' ' ' ~'~ "' ' ' ' '' .~ . ' ' , '' : '' ,. ' . , ~ : ,-' medium is provided with parallel, adjacent record tracks in which information signals and the aforementioned predetermined signals aré recorded. During a reproducing operation, at least one cross-talk predetermined signal which is recorded in at least one adjacent track is reproduced. ~rhis cross-talk predetermined signal is detected and a control signal is produced in response to the level of the detected cross-talk predetermined signal.
The position of the scanning transducer is adjusted wlth respect to the track ~eing scanned in accordance with the control signal.
In one embodiment, the information signals are video signals having periodic horizontal blanking intervals recorded in each record track. The horizontal blanking intervals in a given trac}; are displaced from the horizo~tal blanking intervals in an adjacent track in ~he direction of scanning. This displacement faci~itates the detection of the cross-tal~ predetermined signals which are recorded in predetermined locations of the horizontal blanXing intervals.

More particularly, there is provided:
A method of recording tracking-error correcting signals added to a video signal on a record medium for use in detecting errors in the scanning path of a scanning transducer which scans parallel record tracks across said medium, comprising scanning successive record tracks across said medium to record periodic video signals in said record !
tracks, said video signals containing periodic horizontal-synchronizing pulses; generating pilot signals during pre-determined portions of the horizontal synchronizing signals in said vldeo signals; and recording said pilot signals in said successive tracks such that the portion of a pilot signal in one track is shifted with respect to the position of a pilot signal in an adjacent track.
~ . .
_5_ There is also provided:
A method of correcting tracking-errors of a scanning transducer which scans successive parallel, adjacent recor,~ tracks of a record medium to reproduce video signals therefrom , said video signals including pilot signals recorded dur.ing predetermined portions of the horizontal blanking inter-vals of said video signals, said method comprising reproducing said video and pilot signals when said tracks are scanned, ¦
said reproduced pilot signals including the pilot signal ¦
recorded in the trac~ being scanned by said transducer together with at least one cross-talk pilot signal recorded in at least one adjacent track; detecting said at least one crioss-talk :
pilot signal; producing a control signal in response to the level of the detected cross-talk pilot signal; and adjusting the position of said transducer with respect to said track being scanned by said transducer as a function of said control signal.
There is also provided: - .
Apparatus for recording tracking-error correcting signals on a record medium for use in detecting tracking errors in the scanning path of a transducer as said transducer scans said record medium to reproduce video signals recorded thereon, said video signals being recorded in successive, adjacent, parallel tracks wherein each track is pro~ided with a plurality of horizontal blanking intervals with the horizontal blanking ¦
intervals of one track being offset with respect to the horizontal blanking intervals of an adjacent track, said .
apparatus comprising at least one transducer for recording said video signals onto said record medium; video signal ~:
processing means for supplying a video signal to said trans-ducer for recording on said record medium; and means for ~ , ,.
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.. . . . .. ... . . ... ~ .. .. ~.... . . ..... .

supplying a pilot signal to said transducer during predetermined portions of said horizontal blanking intervals for recording on said record medium.
There is further provided:
Apparatus for correcting tracking errors in a video signal reproducing system of the type wherein at least one transducer scans successive, adjacent, parallel tracks on a record medium in which video signals including horizontal synchronizing signals are recorded, said video signals being provided with pilot signals recorded during certain portions of the horizontal blanking intervals of said video signals, said , apparatus comprising:
transducer means adapted for relative motion with respect to said record medium for reproducing the signals recorded in a given track together with a cross-talk component o~ at least the pilot signals recorded in an adjacent track;
sensing means for sensing said cross-talk component of said pilot signals recorded in said adjacent track~
level detecting means for detecting the level of said sensed cross-talk component of said pilot signals;
control signal generating means for generating a j control signal as a function of the detected level of said sensed cross-talk component of said pilot signals; and adjustable support means for said trans~ucer means, said adjustable support means being responsive to said control I ¦ :
signal to displace said transducer means transversely of said :
given track in accordance with said control signal and in a direction to restore said control signal to a quiescent value.

5~

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BRIEF DESCRIPTION OF THE: DRAI~I~GS
- The following ~etailed descri~t.ionr given by wa~ of. ~
e~ample, will best be understood in conjunct;on with the accompany-in~ drawings in wh;ch:
FIG. 1~ is a schematic top view of rotary head recording/
reproduc;ng apparatus;
FIG. lB is a schematic side view of the apparatus shown .
in FIG. lA; . ! :
FIG. 2~ represents parallel tracks on a record medium having guard bands between a~ cent trac);s; ¦ . . .
. FIG. 2B represents parallel tracl~s on a record medium l .
wherein successive tracks are adjacent each other; I

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. , ~ . , . . ~ . ~.

- ' '': ~ ~ . .

FIGS. 3A-3C are schematic side views of a piezo-electric support member which can be used with the present invention;
FIG. 4~ is a side view of one embodiment of a head support assembly which can be used with the present invention;
FIG. 4B is a bottom view of the assembly shown in FIG. 4A;
FIG. 5 is a block diagram of video signal recording appara~
tus which can be used to record tracking-error correcting signals;
FIGS. 6A-5D are waveform diagrams which are useful in understanding the operation of the apparatus shown in FIG. 5;
FIG. 7 represents different positions of a scanning transducer relative to the record tracks shown, for example, in FIG. 2B;
FIG. 8 is a block diagram of signal reproducing apparatus which can be used to correct tracking errors of a scanning trans-ducer;
FIGS. 9A-9E are waveform diagrams whih are useful in understanding the operation of the apparatus shown in F~G. 8; and FIG. 10 is a graphical representation showing ~he relation-ship between tracking errors and particular s;gnals which are pro-duced by components o~ the apparatus shown in FIG. 8.
DETAILED DESCRIPTION OF CERTAIN PREFERRED E~ODIMENTS
The following detailed description, given by way of example, will best be understood in conjunction with the accompany-ing drawings. For the purpose of simplification, and in order to facilitate an understanding of the present invention, the following description is limited to the environment of a video signal recorder and, more particularly, to a VTR. However, it will become readily apparent that the present invention can be used in other types of signal recorders, such as analog or digital recorders wherein moving heads scan a record medium. Furthermore, although the record medium .

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-~" : ' ' ' ' ' ' 6~

described herein is, illustratively, magnetic tape~ it should be readily apparent that other types of record media, such as ma~Jnetic sheets, magnetic discs, and the li.ke can be used.
Turning now to FIG. lA, there is schematically illus-tra.ted a top view of a typical rotary head scannin~ device, such as a VTR. As is conventional, this devi.ce îs formed with two magnetic record/playback heads la, lb (hereinafter, merely heads) which are adapted for rotation about a central axis. A guide drum

2 is adapted to receive a r cord medium, such as tape 3, wrapped helically thereabout for at least 180. Heads la and lh may be mounted on diametrically opposed arms which are rotated to as to scan successive, parallel, skewed tracks across tape 3~ Alterna-tively, heads la and lb may be mounted on a portion of the guide drum, which portion is adapted to be rotated so as to serve the dual purpose of guiding tape 3 -thereabou-t and rotating heads la and lb so as -to scan para].lel tracks across ~he tape. Thus, the heads rotate in the direction :indicated by the arrow while tape 3 is advanced so as to record signal inforrnati:on thereon.
If, as shown in FIG. lB, guide drurn 2 is formed of two drums 2a, 2b, disposed in face-to-face conflguration and spaced apart so as to define a scanning gap therebetween, tape 3 is helically wrapped about a portion of the surface of the guide.
drum and heads la, lb which are supported by, for example., drum 2a, are rotated to scan parallel tracks across the tape. Although FIG. lA shows the preferred scanning apparatus wherein two heads are used, it is possible that only a single head may be provided.
Nevertheless, if two heads are used, alternate tracks are recorded thereby such that first one track is recorded by head la and then the next adjacent track is recorded by head lb, and then the follow-ing track is recorded by head la, and so on.

' 6~

During a signal reproducing operation, the relative speedof tap~ 3 with respect to heads la and lb is the same as during a sigmal recording operation. A suitable servo control system (not shown) is provided to account for relatively small changes .in tape-drive and head-drive motor speeds, tape shrinkage, tape stretching, differences from the recording apparatus to the reproducing appara-tus, and the like. To this effect, a head-position generator 5 is provided to generate pulsés when hea~s la, lb rotate into pre-determined position, such as when head la first contacts tape 3.
A magnetic element 4 ;s secured to the rotary drive shaft which is used to rotate heads la, lb so as to rotate relative to head-position generator 5 while the heads rotate. Head-position gen-erator 5 may comprise a magnetic pick-up sensor for generating a position detecting pulse when magnetic element 4 rotates therepast.
lS In a typical video recording device, each head records a complete field in a respective record track, and heads la, lb are rotated at a speed of 30 rps. Consequently, the posi.tion detecting pulses generated by pick-up sensor 5 have a frequency of 30 Hz.
As shown in FIG. 2A, video signals are recorded by heads la, lb in parallel slant tracks Tal, Tbl, Ta2, ..~ As one example, head la records alternate tracks Tal, Ta2, ...; and head lb records the remaining alternate tracks Tbl, Tb2, ... In a typical VTR, each track Tal, Tbl, ... has a field of video signals recorded therein such that a plurality cf horizontal line intervals separated ~5 by horizontal blanking intervals is recorded in each track. During a reproducing operation, heads, such as heads la, lb, scan the parallel recoxd tracks Tal, Tbl, ... so as to reproduce the previ-ously recorded video signals. The aforement.ioned servo control system adjusts the relative speed of tape 3 and heads la, lb such that the scanning path traversed by the heads substantially '; ' ' ' :~

coincides with the respective record tracks. However, the servo control system may not be sufficient to achieve precise coincidence between the scanning path and record tracks. This means that the head will not be aligned precisely with a record track and, there-Eor, will include a portion of its ~ir gap which ex-tends beyond the longitudirlal margins of the track. For the embodiment wherein tracks Tal, Tbl, ... are spa~ed from each other by guard bands, as shown in FIG. 2A, this lack of coincidence between the path traversed by the scanning head and the record track may not produce noticeable deterioration in the video picture which ultimately is reproduced. However, if the information density of the magnetic tape is increased, as by recording parallel, adjacent record tracks without separating guard bands therebetween, and by reducing the transport speed of tape 3, the problem of imprecise coincidence between the path or trace of the scanning head and each adjacent record track is noticeable. ~hat i5, if the ~canning head deviates significantly from the reco~d track, undesired cross-tallc s;gnals are picked up from the adjacent track. These cross-talk signals may interfere with the video picture which ultimately is reproduced.
Furthermore, tracking errors of this type may reduce the signal-to-noise ratio, thus degrading the quality of the reproduced video picture.
As a numerical example of the foregoing, the width of each record track shown in FIG. 2A may be 30 microns. Similarly, the width of each guard band also m~y be 30 microns. Hence, the track pitch is 60 microns. Now, if the tape transport speed is reduced to one third of the speed used to record the xecord tracks shown in FIG. 2A, the successive parallel tracks will be adjacent each other as shown in FIG. 2B. Although the inclination of the parallel tracks shown in FIG. 2B closely resembles the inclination :`
_9_ .

shown in FIG. 2A, because of the much hi~her rotary speed of the heads rela-tive to the transport speed of the tape in both examples, it may be appreciated that the track pitch in FIG. 2B is reduced to one third the pitch shown in FIG. 2A. That is, the track pitch, or width of each record track, sho~n in FI~. 2B is 20 microns. If the size of the reproducing head used to reproduce the video signals recorded in the tracks shown in FIG. 2A is equal to the size of the reproducing head used to reproduce the signals recorded in the tracks shown in FIG. 2B, then the gap leng-th is 30 microns. Preferably, when this head is used with the record tape shown in FIG. 2B, the scanning path of the head must be con-trolled so as to scan only a 10 micron width portion of aajacent record tracks. That is, if head lb scans track Tblduring a repro-ducing operation, this head must scan only a 5 micron portion of track Tal and only a 5 micron portion of track Ta2. I~ the scanlling path or trace of head lb deviates from the foregoing limitations, interference due to cross-talk from the adjacent record tracks (tracks Tal, Ta2) tends to deteriorate the video picture which is reproduced.
As mentioned above, the usual servo control system provided with VTR's of the type shown in FIGS. lA and lB may not be capable of controlling the scanning trace of the heads within the afore-noted-limitations. It is one purpose of the present invention to provide an adjustable support assembly for heads la, lb so that the scanning traces of these heads can be adjusted so as to correct ; the tracking errors which may not be fully compensated by the usual servo control system. A preferred embodiment of such an adjustable head support assembly is formed of piezo-electric material which is responsive to a voltage applied thereto so as to bend or deflect accordingly. Thus, if heads la and lb are supported by such piezo-electric material, the controlled deflection thereo~ can be used .

. . - -6~

to compensate for such trackin~ errors.
One type of head support assembly which can be used with the present invention is shown schematically in FIGS. 3A-3C. This assembly is formed of a pair of leaf members 7 and 9, each being constructed of piezo-electric material whose directions of polariza-tion are represented by the illustrated arrows. The opposite surfaces of piezo-electric leaf member 7 are plated with electrodes 6a and 6b, respectively; and the opposite surfaces of piezo-electric leaf member 9 likewise are plated with electrodes 8a and 8b, respec-tively. When piezo-electric leaf members 7 and 9 overlie each other such that electrodes 6b and 8a are in contact, the assembly will deflect if a variable voltage is applied across the respective members. For example, and as shown in FIG. 3B, if voltages are applied to the electrodes in the manner shown, then piezo-electric leaf mem~er 7 tends to e~pand in its lengthwise direction while piezo-electric leaf mer~er 9 tends to compres~. As a re~uJ.t of these oppositely-acting forces, the illustrc~l:ed head support assembly bends, or deflects, by an amount which is a function of the strength of the electric field applied across each member.
The variable voltage source thus repres~nts that a variable electric field can be applied across members 7 and 9 so as to adjustably deflect the head support assembly. If the po]arity of this electric field is reversed, the direction in which the ; assembly bends, or deflects, correspondingly is reversed~
The head support assembly comprised of the pair of piezo-electric leaf members having respectively opposite surfaces plated with electrodes hereinafter is referred to as a bi-morph leaf or bi-morph assembly~
` : -If the direction of polarization of the plezo-elec-tric members is made opposite to each other, that is, if elec~rode 6a of leaf member 7 now contacts electrode 8a of leaf member 9, the manner in which voltaye is applied to th~ bi-morph assembly to 5 e~fect a displa~ement thereof i.s as shown in FI~3C. Hence, a voltage need not be applied to the electrodes which are in common contact with each other, as in the FIG. 3s embodiment. Instead, if a bias voltage, for example, V /2 is applied to electrode 8b and if a variable voltage V is applied to electrode 6b, then the illustrated bi-morph assembly will bend in a downward direction if the variable voltage V is less than the bias voltage Vo/2.
Conversely, the bi-morph assembly will bend in an upward direction if variable voltage V exceeds bias voltage Vo/2. It can be assumed that variable voltage V is variable over a range from zero to VO
volts.
~ practical embodiment o~ a head support assemb].y formed of a bi-m9rph leaf is illustrated in FIGS. ~A and 4B, whi.ch are side and bottom views, respectively. In FIG. 4A, it is assumed that the head support assembly is mounted on -the lower surface of upper, rotatable guide drum 2a (FIG. lB~. The head support assembly includes a mounting base 10 adapted to receive the bi~morph assemhly which may be secured to this mounting base by a suitable adh~sive 11 The bi-morph assembly extends outward from the base toward the periphery of guide drum 2a, and magnetlc head la or lb is mounted on the free end of the bi-morph assembly.
Preferably, damping members 13a and 13b are provided to damp free or resonant oscillation of the bi-morph assembly which may be caused by the forces exerted in response to the bending voltages applied to the respective electrodes. Damping members 13a and 13b are attached to tabs 12a anfl 12b, respectively, these ' ' ' : , ' ' ~ '` ' .' ' ',: "' ' ~ . '. ` ' ' :

G~

tab~ extendiny from a damping member mounting plate 14 which, as shown, extends outwardly from base 10. Dam~iny action is achieved when the damoing members are pressed between the sides of the bi-morph assembl~ and tabs 12a and 12b with suitable force to prevent oscillation but not so g~ea-t as to prevent deflection of the bi-morph assembly in response to the drlve voltage applied thereto.
As also shown, conducting leads are secured to the respective electrodes of the bi-morph assemhly for receiving the drive or deflecting vol-tage.
In accordance with the present invention, the drive voltaye which is applied to the bi-morph asse~bly is produced during a reproducing operation. This dr;ve voltage represents the deviation of the scanning trace of head la, lb from the pre-viously recorded track. The extent of this deviation is determined by detecting the magnitude of a cross-talk component which is picked up by the scanning transducer fxom a track adjacent the particular track which is scanned. For example, and wi~h reference to FIG. 2B, if head lb scans track Tbl, the deviation between the scanning trace of this head and track Tbl can be representea by the level of a cross-talk signal picked up from track Tal and/or track Ta2. It is one aspect of the present invention to record a predetermined signal, such as a pilot signal, together with the video signals which normally are recorded in each track so that, during a reproducing operat;on, a cross-talk comp~nent of the pre-determined, or pilot signal can be detected and used as an indica-tion of the extent of a tracking error.
Referring to FIG. 5, there is illustrated therein a block diagram of video signal recording apparatus which can be used to record both a video signal and a predetermined, or pilot signal on the recording medium. The illustrated recording apparatus is ' ' ' ` ` ' . `

capable oE recording ~oth monochrome (black-and-white) video si~nals and color video signals on the record medium. For the purpose of the present discussion, it will be assumed that this apparatus is supp].ied with a composite color video signal, includ-ing lumlnancc and chrominance components, and -the usual synchron.iz-ing signals, for recording. In one embodiment, the recording apparatus is comprised of a luminance signal channel, formed of a low-pass filter 16, frequency modulator 18 and high-pass filter 19, and a chrominance s;gnal channel formed of a band-pass filter 17, frequency converter 21 and low-pass filter 22. As is conven-tional, the respective circuits in each of the aforementioned chan-nels are connected in series for the purpose of separating the luminance and chrominance signals from each other, and then frequency-modulating the separated luminance signals to a higher frequency band 15 while frequency~converting the chrominance si~nals to a lower fre-quency band. These band-separated s:ignals are co~inea in an add-ing circuit 20 to be supplied to heads la, lb ~or recording on the record medium. In an alternative e~odi:ment of recording appa-ratus, the composite color video signal may be suppliedr through suitable filtering and amplifying circuits, to a :Erequency modulator, and the frequency-modulated composite color video signal then may be recorded on the medium.
A pilot signal oscillator 24 is provided to generate a pilot signal having a predetermîned frequency fp. If the recording apparatus is of the illustrated type wherein a frequency-modulated ; luminance signal and a frequency-converted chrominance signal are combined for simultaneous recording, the frequency fp of the pilct signal generated by pilot signal oscillator 24 preferably is less than the band of frequency-modulated luminance s.ignals and is ; 30 capable of being detected or discriminated from the frequency-converted chromin~nce signals. Pilot si~n~l oscillator 24 is coupled through a gate ~ircuit 25 to an adding circuit 23. Gate circuit 25 is responsive to a gating signal applied thereto so as -to transmit a predetermined duration of pilot signal to adding circu:it 23. It is one feature of the i.llustrated recording appara-tus to record the pilot signal only during predetermined times oE
the video signal. Preferably, and in order to insure that the pilot signal will not interfere with the video si~nal during a reproducing operation, the pilot sianal is recorded during a certain portion of the horizontal blanking interval. For this purpose, the gating signal applied to gate circuit. 25 is derived from the hori-zontal synchronizing signal included in the composite color video signal. Accordingly, a horizontal synchroniæing separator circuit 26 is connected to separate the horizontal synchronizlng signal from the composite color video signal. As shown, horizontal synchroniz-ing separator circui.t 26 is coupled to the output of l.ow-pass fi.lker 16. The separated horizontal synchronizi.ng si`gnal is applied to a monostable multivibrator 27 to -trigger the latter for generating a gating signal which, in turn, is applied to gate circuit 25~
In operation, the luminance and chrominance signal channel.s operate in conventional manner and, therefore, need not he further described. Horizontal synchronizing separator circuit 26 also operates in a conventional manner so as to separate the horizontal signal, shown in FIG. 6A, from the composite color video si.gnal which is applied to input terminal 15. The separated horizontal synchronizing signal triggers monostable multivibrator 27 to produce a gating pulse of limited duration as shown in FIG. 6C~ The pilot siynal, shown in FIG. 6B, is supplied from pilo~ signal oscillator 24 to gate circuit 25 and is gated through the gate circuit during 30 . the interval of the gating pulse of FIG. 6C. Accordingly, the 6~

pilot signal is supplied to adding circui-t 23 during a predeter-mined portion of the horizontal blanking interval, such as durin~
an initial portion of the horizontal synchronizing pulse, as shown in FIG. 6D. The gated pilot signal is combined with the frequency-modu]ated luminance signal and the frequency~converted chrominancesignal for recordin~ on the record medium by heads la and lb durin~
alternate scans of the medium. In one embodiment, this pilot signal is recorded during each horizontal blanking interval. I~oweve~, if desired, the pilot signal may be recorded during selected horizontal blanking intervals. Thus, in successive, ad~acent parallel tracks, a pilot signal is recorded at predet~rmined locations, i.e., during a selected portion of the horizontal blanking interval r Of the horizontal line interval.
As mentioned above, one aspect of this invention is to utilize the cross-talk component of the recorded pilot signal which is picked up from adjacent txacks as cl~ indication of the trackirlg error of the scanning transducer dt~ring a reproducin~
operation. As may be appreciated, if the horizontal blanking intervals in adjacent tracks all are in aliynment in a d~rection tranversely of such tracks, there may be difficulty in discriminat-ing between a cross-talk pilot signal and the pilot signal which is recovered from the track being scanned. This difficulty may be avoided if the pilot signal is of a different frequency for the different tracks. That is, if the pilot signal recorded by head la is of a frequency fpa and if the pilot si~nal recorded by head lb is of a frequency fpb, then suitable frequency detectors can be used to detect the cross-talk pilot signal during signal reproduction. In the preferred embodiment described herein, the frequency of the pilot signal is the same for all tracks. There-fore, in order to facilitate the detection of the cross-talk componen , . . ' ' '` :
- .. . . .

- - . - : .. .

of the pilot signal, the position of the horizontal blanking in-tervals which are recor~ed in one track is shifted or displaced w;th respect to the position of the horizontal blanking intervals recorded in an adjacent tr~ck. This is illustrated in FIG. 7 which shows tracks Tal, Tbl and Ta2, in which are recorded hori-zontal blanking intervals Hl, H2 and H3, respectively. As shown, these horizont~l blanking intervals are not ali~ned. Rather, hori~ontal blanking intervals H2 are displaced or shifted with respect to horizontal blanking intervals Hl, and horizontal blank-ing intervals H3 are displaced, or shifted, with respect to hori-zontal blanking intervals H2. This displacement or shifting of the horizontal blanking intervals relative to each other in success-ive, adjacent tracks, can be attained by suitably selecting the diameter of tape guide drum 2/ by suitably selecting the transport speed of the m~ynetic tape, or by selectin~ other paramet:ers in the VTR, as is well known. For example, in the NTSC system, one frame of video signals is formed of 525 horizontal lin~ intervals.
If a complete field is recorded in a record track, each track will include 262.5 horizontal line intervals. As shown in PIG. 2B, the beginning portion of one track is shiEted relative to the beginning portion of an adjacent track because of the movement of the tape. If this displacement is equal to one-half of a horizontal line interval (0.5 H), then the parallel tracks are recorded with their horizontal blanking intervals aligned with each other in a direction transversely of the tracks. This is the so-called H alignment which is attained by suitably selecting the diameter of the tape guide drum, the transport speed of the tape, or other parameters. Hence, the displacement, or shifting o~ the horiæontal blanking intervals as shown in FIG~ 7 can be achieved in accordance with the selection of one or more of these -17~

6~L

parameters. Preferably, the displace~ent of the horizontal b]anking intervals, that is, the displacement between horizontal bla.nk;.nc3 interval Hl and horizontal blanking interval H2, as well as the di.sp].acemen-t between horizont~l blanking interval. H2 and hor:izontal blanking interval H3 is such that, in this displacement interval,neither a chrominance signal nor a burst signal is recorded.
That is, since the burst signal usually is provided during the back porch of the horizontal synchronizing pulse, the displacement be-tween, for example, horizontal blanking interval Hl and horizontal blanking interval H2 is less than the distance between the leading portion of horizontal blanking interval Hl and the beginning of the burst signal on the back porch of horizontal. blanking interval Hl.
A similar displacement is provided between horizontal blanking intervals H2 and H3. As will soon become apparent, this displace-lS ment enables the cross-talk components of the pilot s.1.gnals to be detected and, fur~hermore, avoids interferer)ce which may be caused by cross-talk between the pilot signal recorded in one track and the burst or chrominance signals recorded .i.n the adjacent track.
Turning now to FIG. 8, there is illustrated a block diagram of apparatus for reproducing the video sign~ls record.ed by the apparatus shown in FIG. 5 and ~or controlling the scanning trace.
of the reproducing head during reproauction~ It will be assumed, for the purpose of the present discussion, that the horizontal : blanking intervals recorded in adjacent tracks are dîsplaced, or ~ 25 shifted from each other, in the manner shown in FIG. 7~ It also; will be assumed that the pilot signals are recorded during eachhorizontal blanking interval at the location represented i.n FIG. 6D. .
The video signal reproducing apparatus includes a luminance signal channel.and a chrominance signal channel coupled to heads la, lb.
The luminance signal channel includes a high-pass filter 31, a ' ' , .

.
- ~

lim:iter 33, a frequency demodulator 34 and a low-pass filter 35, all connected in series as shown, as is conventional. The chromi-nance signal channel includes a low-pass fi.lter 32, a frequency re-converter 37 and a band-pass filter 3~, al] connected in series as shown, and as is conventional. An addi.ng circuit 36 is couplecl to the outputs of the luminance and chrominance si~nal channels so as to recombine the recovered luminance and chrominance components in order to reconstitute the composite color video signal for further application to an output terminal 39.
The reproducing apparatus illustrated in FIG. 8 is compat-ible with the recording apparatus described previously with respect to FIG. 5. Accordingly, if the recording apparatus includes merely a frequency modulator for modulating the composite video signal, that is, if separate luminance and chrominance signal channels lS are omitted in the recording apparatus, the reproducing apparatus likewise may include a ~requency demodul~tor ~or demodula.ting the composite color video signal, thereby omitting the separate lwminance and chrominance signal channels.
The apparatus for controlling the scanning trace of heads la, lb, that is, the tracking-error correctin~ circuitry, is com-prised of a horizontal synchronizing separator circuit 42, mono-stable multivibrators 43, 44 and 45, gate circuits 40 and 41, band-pass filters 46 and 47, level detectors 48 and 49 and a comparator 50. Horizontal synchronizing separator circuit 42 may be simi.lar to aforede5cribed horizontal synchronizing separator cîrcuit 26 and is coupled to the output of the luminance signal channel so as to separate the horizontal synchronizin~ signal from the recovered luminance signal. The output of horizontal synchronizing separator circuit 42 is coupled in common to monostable multivibrators 43 and 45, with monostable multivibrator 43 being further coupled to .

:

monos-table mul-tivibrator 44, Monostable multivihrator 43 is responsive to the separated horizontal synchronizing signal for producing a pulse of prede-termined duration. This pulse is applied to monostable multivlbrator 4~ whi~h, .in turn, is adapted to produce a gating pulse Pl. Depending upon the time constant of monostable mu].tivi.brator ~3, it is appreci.ated that gating pulse Pl is c~elayed from the separated hori~ontal synchronizing signal. In the embodi-ment described herein, this delay is slightly less than a horizontal line interval (lH) and, more particularly, is approximately equal to the delay between horizontal blanking interval H2 and the next succeeding horizontal blanking interval Hl, shown in FIG. 7.
Monostable multivibrator 45 is responsive to the separated hori-zontal synchronizing signal for producing a gating pulse P2 at a time delayed from the start of the separated horizontal synchroniz-ing signal. More particularly, gating pulse P2 is adapted to beproduced at a delayed time approximately correspQndin~ to the delay between hoxizontal blanki.ng interval H2 and horizontal blank-ing interval H3, shown in FIG. 7.
Gate circuits 40 and 41 have signa] inputs connected in common to the output of the chrominance signal channel, ~hese gate circuits being adapted to receive both the chrominance signal and the pilot signal which are transmitted through this chrominance signal channel. Gate circuit 40 includes a gating input adapted to receive gate pulse Pl; and gate circuit 41 similarly includes a gating input adapted to receive gate pulse P2. The outputs of gate circuits 40 and 41 are coupled through band-pass fi].ters 46 and 47, respectively, to level detectors 48 and 49, respectively.
Level detectors 48 and 49 each are comprised of peak level detectors, such as envelope detectors, or the like, adapted to produce signals El and E2, respectively, which are a function of the signal level -20~

' ' ' ' : : .
- . ' :- ., . ~ , : : . : .

... . .. ` ~ - . . : ~ .. :

1113.961 of the pilot signals applied thereto by band-pass filters 46 and 47. For this purpose, the pass-band oF these ~and-pass filters preferably may be relatively narrow so as to pass sub-stantially only the reproduced pilot signals~ As will be described in greater detail below, these band-pass filters pass cross-talk components of the reproduced pilot signals.
Comparator 50 is adapted to compare the signal levels of the passed pilot signals and to produce an output voltage in accordance with the difference therebetween. Accord;ngly, the comparator may comprise a differential amplifier having a pair of inputs adapted to receive signals El and ~2 The output of comparator 50 is used as the drive or deflection voltage V for application to the bi-morph assembly so as to correspondîngly deflect or bend the head support assembly 80 as to adjust the transverse position o heads la, lb relative t:o the record tracks -~ as these heads traver~e such tracks.
The operation of the reproducing apparatus shown in FIG. 8 now will be described. It is recalled that the ~requency fp of the pilot signal which is recorded during the horizontal blanking intervals is less than the frequency band of the frequency-modulatèd luminance signal. Hence, during reproduction, the pilot signal is passed by low-pass filter 32 in the chrominance signal channel. In bne embodiment, this pilot signal i.s frequency converted by a freguency reconverting signal whose frequency is f5 so as to ~ form a freguency-converted pilot signal of a frequency ~fs-fp).
This frequency-converted pilot signal is passed through band-pass filter 38 and applied to adding circuit 36 as well as to gate cir-, , cuits 40 and 41. If desired, suitable circuitry may be providedto prevent this frequency-converted pilot signal from being applied 30 to the adding circuit.

A

~ -21-6~ ' In an alternative embodiment, the reproduced pilot signal which is passed by low pass filter 32 merely is applied dlrectly throu~3h a hand-pass filter ~o gate circuits 40 and 41 without passi.ng through a frequency converting circuit, such as frequency converter 37. In either embodlment, it is appreciated that a detectable pilot signal is applied to gate circuits 40 and 41. Also, in bo-th emb~diments, the pilot signal may be blocked so as not to be applied to adding circuit 36.
Let it first be assumed that head lb scans track Tbl.
Let it further be assumed that, since the length of the gap of this head is greater than the width of track Tbl, the head scans this track symmetrically, as shown in FIG. 7. This corresponds to a desired scanning trace and is assumed to be error-free.
Since substantially equal portions of tracks Tal and Ta2 are scanncd by head lb, it may be appxeciated -that, as track Tbl is ~canned, cross-talk components of the pilot signals recorded in tracks Tal and Ta2 are recovered, which cross-talk components have substantially equal signal levels. When hea~d lb scan.s horizontal blanking interval H2 on track Tbl f the horizon.tal blanking pulse and horizontal synchronizing pulse are reproduced.
Since these signals had been recorded with the frequency-modulated luminance component, they are recovered at the output of low-pass filter 35 and are separated from the luminance component by horizontal synchronizing separator circuit 42. The se.parated signals trigger monostable multivibrator 43 which, in turn, triggers monostable multivibrator 44 to produce a gating pulse Pl.
The time of occurrence of gating pulse Pl i:s delayed from the reproduction of horizontal blanking interval H2~ In particular, if it is assumed that the pilot signal recorded during horizontal blanking interval H2 is represented as signal Sb shown in FIG. 9A, ~ ~ .
: -22-6~L
then ~ating pulse Pl is delayed therefrom, as shown by pulses Pl in FIG. 9B.
The separated horizontal synchronizing signal also tr.i.ycJers rnonostab].e multivlbrator 45 to produce pulses P2 as showr1 in FIG. 9C.
As head lb scans track Tb], first a cross-talk component of the pilot signal, designated S l' recorded in horizontal blank-ing interval Hl is reproduced, then the pilot signal, designated as Sb, recorded in horizontal blanking interval H2 is reproduced, and then the cross-talk component of the pilot signal, designated as Sa2, recorded in horizontal blanking intexval ~13 is reproduced.
The time and amplitude relationship between pilot signals Sal, Sb and Sa2 are shown in FIG. 9A. A comparison of FIGS. 9A-9C lndi-cates that gating pulse Pl substantially co.incides with the cross-talk component of pilot signal Sal, and gating pulse P~ substan-tially coincides with the cross-talk componer)t of pilot signal Sa2.
However, no gating pulse is provided to coincide with.pi:lot signal Sb. Accordingly, gate circuit 40 responds to gat1ng pulse Pl to extract the cross-talk component of pilot signal Sal ~rom the repro-duced video signals; and gate circuit 41 responds to gating pulseP2 to extract the cross-talk component of pilot signal Sal from the reproduced video signal. The extracted pilot signals pass through band-pass f;lters 46 and 47 having signal levels El and E2, respectively, as shown in FIGS. 9D and 9E. These signal levels are detected by level detectors 48 and 49, respectively, and are compared in comparator 50. Since it is assumed that head lb correctly scans track Tbl, si~nal level ~l of the cross-talk component o~ pilot signal Sal is equal to signal level E2 of the cross-talk component of pilot signal Sa2. Accordingly, the differ-ence therebetween is substantially equal to zero. This means that .

` `

6~ .

comparator 50 applies a drive vol~age of vo/2 to the bi-morph assembly, whereby head lb is not deflected d~ring its scanning trace of track Tb1.
Let it now be assurned that head lb deviates from its desired scanrling trace in the manner represented by the left-most example shown in FIG. 7~ Hence, head lb deviates toward track T 1 such that a yrea-ter portion of this track is scanned by the h~ad than track Ta2. As described above, when the horizonta] blanking intervals H2 are scanned, horizontal synchronizing pulses are separated from the reproduced video signals, and monostable multi-vibrators 43, 44 and 45 are triggered so as to produce gating pulses Pl and P2, as shown in FIGS. 9B and 9C. Gating pulse Pl actuates gate circuit 40 to gate the cross-talk component of pilot signal Sal, recorded in track Tal and reproduced by head lb.
Similaxly, gating pulse P2 actuates gate circl:lit 41 so a8 to pass the cross-talk component of pilot signal Sa~ which is recorded in track Ta2 and is reproduced by head lb. In view of the deviation of head lb with respect to its desired scanning trace, the levels of the gated pilot signals, as passed through band-pass filters 46 and 47 are as shown in FIGS. 9D and 9E, respectively. Conse-quently, signal level El, detected by level d~tector 48, exceeds signal leveL E2, detected by level detector 4~. These detected signal levels are compared in comparator 50 and the difference therebetween is used to derive the drive voltage which is applied to the bi-morph assembly. As may be appreciated, this drive volt-age is of a polarity and magntiude so as to deflect the bi-morph assembly in a direction whereby head lb is restored to its desired scanning trace. That is, head lb is deflected in a direction to minimize the tracking error. This means that the detected signal ~ 30 levels of the cross-talk pilot signaIs which are reproduced from : - .

' . .
:. . . . :, .: . . . . ~ - , . . . , - ..
.. . . .

6~

tracks Tal and Ta2 become equal to each other.
Now let it be assumed that head lb deviates from its des:ired scanni.ng trace in the manner represented by the right-most example shown in FIG. 7 wherein he~d lb overlies a greater portion of track T 2 than track T 1 It is appreciated that, in accordance with this assumed tracking error, the level of the cross-talk component of pilot signal S 1' which is recorded in track Tal and reproduced by head lb, is less than the cross-talk com~onent of pilot signal Sa2, recorded in track Ta2 and repro-duced by head lb. Co~parator 50 senses that signal level E2exceeds signal level El and applies a drive voltage to the bi-morph assembly having a magnitude and polarity which deflects the bi-morph assembly in a direction so as to restore head lb to its correct scanning trace.
'rhe relationship between the detected signal levels of the cross-talk components of the pilot signals which are recorded in tracks adjacent track Tbl and the track.ing error or deviation in head lb as it scans track Tbl is graphically depicted i.n FIG. lO
and particularly the solid lines shown therein. Thus, when si.gnal . level El is equal to signal level E2, the tracking error, or deviation, is equal to zero ~en.signal level E2 exceeds signal level El, the tracking error is in one direction Conversely, if signal level El exceeds signal level E2, the tracking error is in the opposite direction. As an alternative embodiment, the gap length of head lb (and head la) may be equal to the width. of a record track. With such a construction, it is appreciated that a c.ross-talk component can be recovered from only one of the adjacent tracks and not from both. That is, if head lb traverses its correct scanning trace, no cross-talk component of the pilot signals will be reproduced, and E2=El=0. However, if a cross-talk ~ :

6~L

component of a pilot signal is detected with a level equal to E2, then a tracking error is present wherein head lb overlaps with a port.i.on of trac~ Ta2 Conversely, if the cross--talk component of pilot signal S 1 is reproduced with a signal :I.evel E1, then head lb overlaps with a portion of track T 1 Hence, detected signal levels E2 and E1, which may be of opposite polarities, can be used to derive respective drive votlages to he applied to the bi-morph assembly so as to deflect head lb in a direction to correct the tracking error. The relationship between signal levels El and E2 and the tracking error for the construction wherein the gap length of héad lb is substant.ially equal to the width of the record track is represented by the broken lines shown in FIG. 10. As may be appreciated, with this construction, ..
a diode switching arrangement may be provide~l to selecti:v~ly apply signals El and E2 to the bi.-morph assembly as a drive voltage there-for; or, alternatively, comparator 50 may be used in a manner similar to that described hereinabove.
While the present invention has been particularly shown and described with reference to preferred embodiments and applica-tions thereof, it should be readily apparen-t to one of ordinary : skill in the art that various modifications in form and details may be made without departing from the spirit and scope of the invention. For example, although two scanning heads la, lb have been described, it is appreciated that the tracking-error correcting technique disclosed herein is equally applicahle to a recording/
reproducing device employing only a single head, or to such a device employing more than two heads. Also, and with reference to FIG. 8, horiæontal synchronizing separator circuit 42 has been shown as being connected to the output o~ low-pass filter 35 so as to receive the recovered, demodulated horizontal synchronizing signal. If desired, a suitable frequency detector or discriminator may b~ coupled to the output of limiter 33 and -tuned to the partic-ular frequency which represents -the horizontal synchronizing signals.
Such a frequency detector or discriminator can he used to tri~ger monostable multivibrators 43-45, in a manner similar to -that de-scribed above. Still further, the pilot signal which is recorded during predetermined portions of the horizontal blanking intervals need not be generated solely by pilot signal oscillator 24 (FIG. 5) As an alternative, the ~urst signal which normally is provided on the back porch of the horizontal synchronizing signal can be used as the pilot signal. In such an alternative, the burst signal recorded in the displaced, or shifted horizontal blanking intervals Hl, H2 and H3 can be detected such that the signal levels of the cross-talk components of such burst signals may be used to repre-~en~ the extent of the tracking error of the scanning head, thisoperation being performed in a manner quite s;milar to the fore-going operation discussed in conjunction with the embodiment shown in FIG. 8. Additionally, although the bi-morph assembly is preferred for the head support assembly, other adjustable head support structures can be used, if desired.
The present invention need not be limited only to an NTSC-type color video signal. Rather, the present invention is applicable to the PAL system and SECAM system as well~ As men-tioned previously, tracking-error correction can be attained if the recorded and reproduced video signals are monochrome signals.
Still further, the luminance and chrominance sîgnal channels in both the recording and reproducing apparatus may be of the type wherein crosstalk components which are picked up from adjacent tracks are suppressed. For example, the azimuth angles of heads la and lb may differ from each other so that a cross-talk .
:: -, - .

6~

component of -the luminance signal picked up from an adjacent track is suppressed by reason of the attendant azimuth loss.
Cross-talk components of the chrominance si~nal may be suppressed by providinc3 di.fferent frequency-convertiny carriers in the record-ing apparatus, the frequencies of these carriers exhibiting aninterleaved relationship. By usincJ this technique, cross-talk components which are reproduced from adjacent tracks can be eliminated by providing a comb filter through which the repro- ..
duced chrominance components are passed.
10Hence, it may be appreciated that tracking errors are detected during each horizontal line interval so that heads la and lb can be suitably controlled so as to scan a correct trace across each record track during a reproducin~ operation. This tracking error correction system is of part:icular advantage when the width of each record track is reduced and the tape tran.spoxt ~peed is of a relatively low value so as to .increase the recording density, and thus the recording time, for the record medium~
It is,therefore, intended that the appended claims be.
interpreted as including all of the aforedescribed changes and modifications, as well as various other such changes which will become apparent to one of ordinary skill in the art. :

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of recording tracking-error correcting signals added to a video signal on a record medium for use in detecting errors in the scanning path of a scanning transducer which scans parallel record tracks across said medium, comprising scanning successive record tracks across said medium to record periodic video signals in said record tracks, said video signals containing periodic horizontal synchronizing pulses; generating pilot signals during pre-determined portions of the horizontal synchronizing signals in said video signals; and recording said pilot signals in said successive tracks such that the portion of a pilot signal in one track is shifted with respect to the position of a pilot signal in an adjacent track.

2. The method of Claim 1 wherein a plurality of horizontal line intervals of said video signal is recorded in each record track on said record medium.

3. The method of Claim 2 wherein the starting point of one track is displaced from the starting point of an adjacent track in the direction of scanning of said tracks by an amount to shift the positions of the horizontal synchronizing signals in said one track with respect to the positions of said horizontal synchronizing signals in said adjacent track.

4. The method of Claim 1 wherein said video signals are color video signals containing luminance and chrominance components, periodic horizontal synchronizing signals, and burst signals; and wherein said burst signals constitute said pilot signals.

5. A method of correcting tracking-errors of a scanning transducer which scans successive parallel, adjacent record tracks of a record medium to reproduce video signals therefrom , said video signals including pilot signals recorded during predetermined portions of the horizontal blanking inter-vals of said video signals, said method comprising reproducing said video and pilot signals when said tracks are scanned, said reproduced pilot signals including the pilot signal recorded in the track being scanned by said transducer together with at least one cross-talk pilot signal recorded in at least one adjacent track; detecting said at least one cross-talk pilot signal; producing a control signal in response to the level of the detected cross-talk pilot signal; and adjusting the position of said transducer with respect to said track being scanned by said transducer as a function of said control signal.

6. The method of claim 5 wherein the level of the detected cross-talk pilot signal is proportional to the tracking error of said transducer relative to the track being scanned thereby; and wherein said position of said transducer is adjusted so as to vary said level of said detected cross-talk pilot signal in a direction to minimize said tracking error.

7. The method of Claim 6, wherein another track is provided adjacent said track being scanned by said transducer;
said step of reproducing includes reproducing another cross-talk pilot signal from said other adjacent track; said step of detecting includes detecting said other cross-talk pilot signal;
and wherein said control signal is proportional to the levels of the first-mentioned and other pilot signals.

8. The method of claim 7 wherein said step of producing a control signal comprises generating first and second signals proportional to the peak levels of said first-mentioned and other pilot signals, respectively comparing said first and second signals to each other; and producing said control signal as a function of the difference between said first and second signals.

9. The method of Claim 8 wherein said step of detecting comprises sensing the horizontal blanking intervals reproduced during the scanning of a track; generating periodic gating pulses in response to said sensed horizontal blanking intervals; and gating the first-mentioned and other pilot signals from the reproduced video signals in response to said gating pulses.

10. The method of Claim 9 wherein the horizontal blanking intervals recorded in one track are displaced from the horizontal blanking intervals recorded in adjacent tracks in the direction of scanning; and wherein said gating pulses are generated in time-displaced relation to each other such that a first set of gating pulses substantially coincides with the cross-talk pilot signals reproduced from one adjacent track and a second set of gating pulses substantially coincides with the cross-talk pilot signals reproduced from the other adjacent track.

11. The method of Claim 5 wherein said video signals are color video signals containing luminance and chrominance components, periodic horizontal synchronizing signals, and burst signals; and wherein said burst signals constitute said predetermined signals.

12. Apparatus for recording tracking-error correcting signals on a record medium for use in detecting tracking errors in the scanning path of a transducer as said transducer scans said record medium to reproduce video signals recorded thereon, said video signals being recorded in successive, adjacent, parallel tracks wherein each track is provided with a plurality of horizontal blanking intervals with the horizontal blanking intervals of one track being offset with respect to the horizontal blanking intervals of an adjacent track, said apparatus comprising at least one transducer for recording said video signals onto said record medium; video signal processing means for supplying a video signal to said trans-ducer for recording on said record medium; and means for supplying a pilot signal to said transducer during predetermined portions of said horizontal blanking intervals for recording on said record medium.

13. The apparatus of Claim 12 wherein said means for supplying a pilot signal comprises an oscillator for pro-ducing a signal of predetermined frequency; horizontal synchronizing signal separating means for separating the horizontal synchronizing signal from said video signal;
gating means coupled to said oscillator and responsive to said separated horizontal synchronizing signal for gating said signal of predetermined frequency; and means for applying said gated signal of predetermined frequency to said transducer.

14. The apparatus of Claim 13, wherein said means for supplying comprises adder means having an input coupled to said video signal processing means, another input coupled to said gating means, and an output coupled to said transducer.

15. The apparatus of Claim 12 wherein said video signal is a color video signal including luminance and chrominance components and a burst signal; and wherein said pilot signal is constituted by said burst signal.

16. Apparatus for correcting tracking errors in a video signal reproducing system of the type wherein at least one transducer scans successive, adjacent, parallel tracks on a record medium in which video signals including horizontal synchronizing signals are recorded, said video signals being provided with pilot signals recorded during certain portions of the horizontal blanking intervals of said video signals, said apparatus comprising:
transducer means adapted for relative motion with respect to said record medium for reproducing the signals recorded in a given track together with a cross-talk component of at least the pilot signals recorded in an adjacent track;
sensing means for sensing said cross-talk component of said pilot signals recorded in said adjacent track;
level detecting means for detecting the level of said sensed cross-talk component of said pilot signals;
control signal generating means for generating a control signal as a function of the detected level of said sensed cross-talk component of said pilot signals; and adjustable support means for said transducer means, said adjustable support means being responsive to said control signal to displace said transducer means transversely of said given track in accordance with said control signal and in a direction to restore said control signal to a quiescent value.

17. The apparatus of Claim 16 wherein said transducer means comprise first and second transducers, each reproducing the signals recorded in alternate tracks together with the cross-talk components of the pilot signals recorded in both alternate tracks adjacent said given tracks; said sensing means senses the cross-talk components of said pilot signals re-produced from both adjacent tracks; said level detecting means detects the respective levels of the cross-talk components of said pilot signals reproduced from both adjacent tracks; and said control signal generating means generates said control signal as a function of the detected levels of the cross-talk components of said pilot signals reproduced from both adjacent tracks.

18. The apparatus of Claim 17, wherein said control signal generating means comprise comparator means for receiving the respective detected levels of the cross-talk components of said pilot signals reproduced from both adjacent tracks and for generating said control signal in accordance with the difference therebetween.

19. The apparatus of Claim 16 wherein the horizontal blanking intervals recorded in said given track are displaced with respect to the horizontal blanking intervals recorded in said adjacent track; and wherein said sensing means comprises horizontal synchronizing signal separating means for separating the horizontal synchronizing signals from the video signals reproduced from said given track, gate pulse generating means for generating gate pulses in response to said separated horizontal synchronizing signals, said gate pulses being in timed coincidence with the cross-talk components of the reproduced pilot signals, and gating means for receiving said reproduced video signals and responsive to said gate pulses to separate said cross-talk components of said pilot signals.

20. The apparatus of Claim 19 wherein said video signals are color video signals including luminance and chrominance components and a burst signal; and wherein said pilot signals are constituted by said burst signal.

21. The apparatus of Claim 16 wherein said adjustable support means comprises electrically responsive flexure means upon which said transducer means is mounted, said flexure means flexing in response to said control signal to displace said transducer means.

22. The apparatus of Claim 21 wherein said flexure means is formed of piezo-electric material.

23. The apparatus of Claim 22 wherein said piezo-electric material comprises a leaf assembly formed of two leaves of piezo-electric material, each having top and bottom surfaces provided with electrodes, the two leaves being in overlying relationship with each other.

24. The apparatus of Claim 16 wherein said level detecting means comprises peak level detecting means for detecting the peak level of the cross-talk components of the reproduced pilot signals.