Apparatus and methods for recording information signals and tracking signals on magnetic tape

Abstract: An apparatus for recording information and tracking signals on magnetic tape (11) includes first and second magnetic heads (H L , H T ) for recording the information signals on the tape (11). The heads (H L , H T ) are mounted for rotation about an axis for scanning the tape (11) for recording the information signals in successive tracks, and are disposed at respective positions along the axis separated from one another by substantially one track pitch and have respectively different azimuth angles. A third magnetic head (H L ′) records the tracking signals on the tape (11) and is mounted at a position rotationally substantially opposite the first head (H L ), and is substantially aligned therewith. The tracking signals are recorded in at least some of the successive tracks with azimuth angles substantially the same as those of the information signals in adjacent ones of the successive tracks.

Description: This invention relates to apparatus and methods for recording information signals and tracking signals on magnetic tape. In video recording, video signals are recorded on a magnetic tape in successive tracks with the use of a helical scan rotary head assembly. The video signals may be recorded either in analogue or digital form, the latter providing improved signal quality upon signal reproduction. In reproducing the signals, it is essential that the oblique tracks as recorded are accurately scanned so that the recorded signals are faithfully reproduced. Accordingly, tracking control is employed to ensure that the previously recorded tracks are accurately followed upon reproduction. Digital audio tape (DAT) apparatus typically utilize similar tracking control techniques where the audio signals are recorded in oblique tracks. In one type of tracking control arrangement, proper positioning of the heads with respect to the oblique tracks is carried out with the assistance of a control signal recorded along a longitudinal edge of the magnetic tape. This longitudinally recorded control signal is reproduced by a stationary head; and tape movement is adjusted if there is a phase difference between the reproduced control signal and a position signal representing the rotary position of the heads. However, this technique requires the use of a stationary head which is used for no other purpose. This head adds to the overall cost of the signal recording/playback apparatus and, more importantly, it impedes miniaturization of that apparatus. If the stationary head can be eliminated, the overall size of the apparatus can be reduced correspondingly. We have proposed a technique for carrying out tracking control utilizing tracking control signals mixed with information signals in the oblique tracks (Japanese patent specification JP-A-59112406). This permits the stationary head to be eliminated by utilizing the transducer which reproduces useful information to reproduce the tracking control signals as well. Digital video and digital audio recording are particularly suited for this approach because digital information signals are easily multiplexed with control signals without loss of useful information, they may be time-base compressed easily and they may be readily processed. Accordingly, in a particular track, a tracking control signal may be recorded in a restricted region apart from other regions of the track where digital information signals are recorded. In one implementation of this proposal, a pilot signal is recorded in the tracks independently of the digital signals. Advantageously, digital video and digital audio signals may be recorded in tracks having no guard bands between them. While this increases the amount of magnetic tape made available to record useful information, it is essential to provide precise tracking control as the playback heads scan the respective tracks. Typically, the heads used for recording and/or reproduction exhibit a gap length larger than the width of a track, which means that an edge of a preceding track is overwritten when the next adjacent track is recorded. This also means that when a playback head is in proper alignment with the pre-recorded track, the signals recorded in both adjacent tracks are picked up as cross-talk components. This phenomenon of cross-talk pick-up is used to detect tracking errors and to provide proper tracking control of the scanning heads. In the arrangement mentioned above, wherein pilot signals of a predetermined frequency are recorded in restricted regions of alternate tracks, a pair of heads having respectively different azimuth angles is used to scan two adjacent tracks substantially simultaneously. Hence, when one head scans the track in which the pilot signal is recorded, the other head scans the adjacent track which has no pilot signal therein. These two heads are mounted on the same rotary head assembly, such as a rotary head drum, and are relatively closed spaced thereon. The head which scans the track having no pilot signal therein will pick up, as a cross-talk component, the pilot signal recorded in an adjacent preceding track as well as the pilot signal recorded in an adjacent following track. If the magnitude of the cross-talk pilot signal picked up by this head from the preceding track is equal to the magnitude of the pilot signal picked up from the following track, the heads are in proper alignment with respect to the tracks scanned thereby. A tracking error is detected if the cross-talk pilot signal magnitudes from the preceding and following tracks differ from each other. In that event, the tape transport is accelerated or decelerated to being the heads back into proper tracking alignment. The foregoing technique utilizing a single pilot signal frequency is relatively simple to implement as it uses the constant spacing of the heads for detecting tracking errors. However, alternate tracks are recorded by each of the heads, so that the signals of successive tracks have different respective azimuth angles. Upon reproduction, the heads scan respective tracks in which signals are recorded with azimuth angles corresponding to those of the heads. Consequently, the pilot signals are detected as cross-talk by a magnetic head having a different head azimuth angle and their magnitudes, thus, are attenuated. Even although the frequency of the pilot signal is selected to minimize azimuth loss, it is nevertheless relatively difficult to detect such cross-talk pilot signals. This tends to reduce the detection accuracy of the pilot signals and to degrade the tracking control function. The reduction in sensitivity to the pilot signals due to azimuth loss can become significant where the difference in the azimuth angles is large or the track width is narrow. According to the present invention there is provided an apparatus for recording information signals and tracking signals on magnetic tape, the apparatus comprising: first and second magnetic head means for recording said information signals on said magnetic tape; mounting means for mounting the first and second magnetic head means for rotation about an axis for scanning said tape with said first and second magnetic head means to record said information signals in successive tracks on said tape; said first and second magnetic head means being disposed at respective positions along said axis separated from one another by substantially one track pitch and having respectively different azimuth angles; third magnetic head means for recording said tracking signals on said tape, said third magnetic head means being mounted by said mounting means at a position rotationally substantially opposite a rotational position of said first magnetic head means and substantially axially aligned therewith; and a signal source for supplying said first and second magnetic head means with said information signals and said third magnetic head means with said tracking signals. In an embodiment of the invention, the azimuth angle of the third magnetic head means may be selected to record the tracking control signals so that their azimuth is substantially the same as that of the reproducing head as it scans adjacent tracks to detect the information signals recorded therein. Therefore, the tracking control signals can be detected as cross-talk from the adjacent tracks without azimuth loss. According to the present invention there is also provided a method of recording information signals and tracking signals on magnetic tape, comprising the steps of: recording said information signals in successive tracks on said tape with the use of first and second magnetic head means mounted for rotation about an axis at respective axial positions spaced by substantially one track pitch and having respectively different azimuth angles, such that said information signals are recorded with correspondingly different azimuth angles in successive tracks; and recording said tracking signals in at least some of said successive tracks with azimuth angles substantially the same as those of said information signals in adjacent ones of said successive tracks. Therefore, in an embodiment of the invention, as the information signals in a given track are reproduced by a magnetic head whose azimuth is selected to correspond with that of the information signals, the azimuth angles of the tracking signals in the adjacent tracks will substantially correspond with that of the reproducing head so that the tracking signals can be detected without azimuth loss. The invention will now be described by way of example with reference to the accompanying drawings, throughout which like parts are referred to by like references, and in which: Figure 1 is a schematic representation illustrating a rotary head drum which may be used in carrying out the aforementioned prior proposal; Figure 2 is a schematic representation of recording tracks scanned by a pair of playback heads in the aforementioned prior proposal; Figure 3 is a schematic representation of an embodiment of apparatus for recording information and tracking signals on video tape including a rotary head drum and in accordance with the present invention; Figure 4 is a schematic representation of recording tracks formed in one mode of operation by the rotary head drum of Figure 3; and Figure 5 is a schematic representation of recording tracks formed in a second mode of operation by the rotary head drum of Figure 3. Before describing the present invention, a detailed explanation of a prior proposal for detecting tracking errors will be explained below in conjunction with Figures 1 and 2. Figure 1 is a schematic representation of a rotary head assembly wherein a pair of playback heads H L and H T having different respective azimuth angles are mounted on a rotary head drum 1 about which a magnetic tape 2 is partially wrapped. The heads H L and H T are designated leading and trailing heads, respectively, and are closely spaced so as to be angularly separated by a relatively short distance GL. In addition, and as will be best appreciated by reference to Figure 2, the heads H L and H T are offset from each other in the axial direction of the drum 1. This offset is substantially equal to the pitch of the tracks scanned thereby. Although Figure 1 illustrates the tape 2 as being wrapped about a peripheral surface of the drum 1 by an angular extent of about 180°, it will be appreciated that this wrap angle may be either greater or smaller. The leading and trailing heads H L and H T function to scan a pair of tracks substantially simultaneously at each rotation of the drum 1. The arrangement shown in Figure 1, wherein a pair of heads is mounted on a rotatable drum in closely spaced but axially offset relationship offers significant advantages over previously proposed mounting arrangements wherein two heads are mounted 180° apart. Tracks which are recorded by diametrically opposed heads may not be in alignment with each other, because the rotary movement of the drum to scan one head across the tape may not be precisely the same as the rotary movement thereof to scan the other head. This difficulty is, of course, avoided when the heads are closely spaced to each other because both heads will be subjected to the very same irregularities that may be present in the drum's rotation. Therefore, the scanning trace of the head H L is practically identical to the scanning trace of the head H T , and the resultant tracks scanned thereby are in precise alignment. Good effects are achieved even if the track pitch is made very small. The track pattern scanned by the heads H L and H T in Figure 1 is illustrated schematically in Figure 2. In this track pattern, a pilot signal of frequency f₀ is recorded in alternate tracks, such as in odd tracks, T₁, T₃, T₅, etc. In accordance with the proposal made heretofore, the duration of the pilot signal is controlled such that the pilot signal is recorded in a restricted region in a track. The frequency of the pilot signal is about several hundreds of kHz, but its frequency is selected to minimize azimuth loss. When the signals are reproduced from the magnetic tape recorded in the manner illustrated in Figure 2, pilot signal f₀ is reproduced when the head H L reaches a point t₀ in the track T₁. Because of the spacing GL between the heads H L and H T , the head H T reaches the point t₀′, in the track T₂ when the head H L first detects the pilot signal. It is seen that the points t₀ and t₀′ are spaced apart by the distance GL, the same spacing as between the heads H L and H T . It is recognized that, when the head H L first detects the pilot signal, the head H T is sufficiently distant therefrom as not to pick up a pilot signal cross-talk component, as yet. Rather, it is not until the head H T advances to the position t₁ in the track T₂ that a cross-talk pilot signal component will be picked up by the head H T from the adjacent track T₃. It is seen that the head H T reaches the point t₁ at a delayed time t a from the point t₀′. That is, at this delayed time t a , the head H T picks up a cross-talk pilot signal component from only one adjacent track, namely the right track T₃. From Figure 2, it is apparent that the head H T reaches a portion of the track T₂ whereat pilot signals f₀ are picked up as cross-talk components simultaneously from the left adjacent track T₁ and from the right adjacent track T₃. During the time that the pilot signal is picked up from both adjacent tracks, a determination cannot be made with respect to a tracking error. Hence, the tracking error detecting circuitry normally used with the arrangement shown in Figure 2 is disabled or otherwise inhibited during the period of time that the head H T picks up pilot signal cross-talk components from both tracks adjacent to the track being scanned thereby. When the head H T reaches the point t₂ as it scans the track T₂, the pilot signal cross-talk component picked up from the right adjacent track T₃ no longer is detected, and the pilot signal cross-talk component now is picked up from only the left adjacent track T₁. Figure 2 illustrates that the head H T arrives at the point t₂ at a delayed time t b from the point t₀′. Preferably, the pilot signal cross-talk component picked up from, for example, the track T₃ is detected separately from the pilot signal cross-talk component picked up from the track T₁. A tracking error is determined by sensing the difference between the separately detected pilot signal cross-talk components. For example, if the magnitude of one pilot signal cross-talk components exceeds the magnitude of the other, it is concluded that the heads H L and H T are not properly centred on the tracks and the tape 2 is accelerated or decelerated to effect a shifting in the heads H L and H T relative to the tracks scanned thereby. Hence, tracking errors are corrected. The apparatus of Figure 1 utilizes the same head to record both the information and pilot signals in each track. When the signals are reproduced utilizing a similarly constructed rotary head drum, each track is scanned by a head having an azimuth angle corresponding with that of the signals recorded in the track. Accordingly, the tracking signals picked up by the head as cross-talk from adjacent tracks have a different azimuth angle, so that their magnitude as detected by the head is attenuated. This can degrade the tracking operation, especially where the track pitch is small or the difference in the azimuth angles is large. Embodiments of the present invention can overcome this difficulty associated with the proposal illustrated in Figures 1 and 2. A preferred embodiment of the present invention will now be described with reference to Figures 3 to 5. With reference to Figure 3, a rotary head drum 10 of a digital video tape recorder is illustrated therein. A magnetic tape 11 is shown wound about the head drum 10 for recording a digital video signal thereon. A first set of magnetic recording heads includes a leading head H L having a first azimuth angle and mounted on the periphery of the head drum 10 in a leading position, and a trailing head H T positioned on the periphery of the head drum 10 in a trailing position with respect to the leading head H L and having a second azimuth angle different from that of the leading head H L . The leading head H L and the trailing head H T are angularly separated by a distance GL and arranged at respective axial positions with respect to the axis of rotation of the head drum 10 separated by a distance of one track pitch. The magnetic heads H L and H T together form a first set of double azimuth heads which serve to record adjacent oblique tracks on the tape 11 as the head drum 10 rotates past the tape 11 as it is transported about the surface of the head drum 10. A second pair of double azimuth heads is positioned on the periphery of the head drum 10 at a rotational position opposite that of the first set of double azimuth heads. The second set includes a leading head H L ′ and a trailing head H T ′, the leading head H L ′ having an axial position corresponding with that of the trailing head H T of the first set. Like the first set of double azimuth heads, the heads of the second set are axially spaced by one track pitch and are angularly separated by a distance GL. The leading head H L ′ of the second set has an azimuth angle corresponding with that of the leading head H L of the first set, while the trailing head H T ′ of the second set of has an azimuth angle corresponding with that of the trailing head H T of the first set, so that the heads H L ′ and H T ′ of the second set have respectively different azimuth angles. The embodiment of Figure 3 is provided with two modes of operation. In the first mode of operation, it is operative to either record or reproduce an NTSC-type video signal in digital form. In this mode, only the heads H L and H T are employed to record the video signal. In a second mode of operation, it is operative to record a high-definition video signal in digital form with the use of all four heads mounted on the head drum 10. In the first mode of operation, the first set of heads H L and H T are supplied with the digital video signal from a signal source 20 through a rotary transformer (not shown for purposes of simplicity and clarity) for recording on tape 11, while the second set of heads H L ′ and H T ′ are supplied with only a pilot signal from the signal source 20 through a rotary transformer for recording on the tape 11. In this mode of operation, the tape 11 is transported at a first speed such that the magnetic heads H L and H T of the first set respectively scan first and second oblique tracks on the tape, while at a subsequent time when the drum 10 has rotated 180° the heads H L ′ and H T ′ of the second set respectively scan the second track formed by the head H T and a third track which will be scanned subsequently by the head H L . In the second mode of operation the tape 11 is transported at a second speed twice the first speed so that first to fourth oblique tracks are scanned by the heads H L , H T , H L ′ and H T ′ in that order. In the second mode, the signal source 20 supplies the digital video signals to all four heads for recording on the tape 11. With reference now to Figure 4, the pattern of oblique trans formed by the Figure 3 embodiment in the second mode of operation is illustrated schematically therein. As shown in Figure 4, the tape 11 is transported in a direction indicated by the arrow, so that during a first 180° of rotation of the head drum 10 the heads of the first set H L and H T respectively form oblique tracks T L and T T on the tape 11. During the immediately subsequent 180° of rotation of the drum 10, the second set of heads H L ′ and H T ′ respectively form a second pair of oblique tracks T L ′ and T T ′. Thereafter the first and second sets of heads alternately record corresponding pairs of tracks in the tape 11. Accordingly, in the second mode of operation, twice as many tracks are formed as in the first mode in a given time period, thereby making it possible to record substantially double the amount of the information as in the first mode for an identical time period for recording the relatively large amount of information included with a high definition video signal. The first mode of operation will now be described with reference to Figure 5. In this mode, the first set of heads H L and H T serve only to record the digital video data in data regions T D of each track, while the second set of heads H L ′ and H T ′ serve to record only a tracking pilot signal f₀ in separate pilot signal recording regions T P of each track. As shown in Figure 5, the leading head H L and the trailing head H T during a first half cycle of the head drum's rotation record the digital video data in regions T D of the tracks T₁₁ and T₁₂, respectively. During the next half cycle of the head drum's rotation, the leading head H L ′ and the trailing head H T ′ record pilot tracking signals in the regions T P respectively in the track T₁₂ formed one half cycle before by the trailing head H T and in a track T₁₃ which will be scanned by the leading head H L of the first set in the next half cycle of the drum's rotation. As the drum 10 continues to rotate, the first set of heads H L and H T scan a subsequent pair of tracks T₁₃ and T₁₄ recording the digital video data in the regions D separated from the regions T P , and thereafter, the second set of heads H L ′ and H T ′ respectively scan the track T₁₄ and a following track T₁₅ to record the tracking pilot signal f₀ in respective regions T P of these tracks. It will be appreciated that the first and second sets of heads will continue alternately to scan the magnetic tape 11 in the foregoing manner so that each set of heads scans a pair of tracks displaced by one track pitch from the pair of tracks scanned by the other set during the immediately preceding half cycle of the drum's rotation. It will also be appreciated that further portions of the track are available for recording data, such as the portion of each track between the data region D and the pilot signal recording region T P . Since the azimuth angles of the leading heads T L and T L ′ are the same, while the azimuth angles of the trailing heads T T and T T ′ are the same, but different from those of the leading heads, and since the leading head of each set records its signals in a track scanned by the trailing head of the other set, it will be appreciated that the signals recorded in the data and pilot signal regions of each track possess different respective azimuth angles In addition, since the leading and trailing heads of each set scan tracks adjacent those scanned by the leading and trailing heads of the other set, respectively, the pilot signals recorded in the regions T P of each track have the same azimuth angle as the video data D recorded in the adjacent tracks. In reproducing the data recorded on the respective tracks T₁₁, T₁₂, T₁₃, ... formed on the tape 11 in accordance with the first mode of operation, only the leading head H L and the trailing head H T of the first set are employed. Each of the leading and trailing heads H L and H T scans a track in which the video data D has the same azimuth angle as the scanning head. Accordingly, the pilot signal recording regions T P of the tracks adjacent to that scanned by each head likewise have the same azimuth angle as such head. Since the pilot signals are reproduced as cross-talk by a head scanning the data of an adjacent track but possessing the same azimuth angle as the cross-talk pilot signals, the head is relatively more sensitive to the pilot signals and is capable of more accurately reproducing them as compared, for example, with apparatus explained above in connection with Figures 1 and 2. With reference again to Figure 5, when the heads H L and H T respectively scan odd and even numbered tracks, the pilot signal f₀ is reproduced when the head H L reaches a point t₁₀ in the track T₁₁. Since the heads H L and H T are spaced apart by the distance GL, the head H T reaches a point t₁₀′ in the track T₁₂ when the head H L first detects the pilot signal. Due to the spacing of the heads H L and H T , the head H T does not at that time pick up a pilot signal cross-talk component. It is not until the head H T advances to the position t₁₁ in the track T₁₂ that a cross-talk pilot signal component is picked up by this head H T from the adjacent track T₁₃. It will be seen that the head H T reaches the point t₁₁ at a delayed time t x from the point t₁₀′. That is, at this delayed time t x , the head H T picks up a cross-talk pilot signal component from only one adjacent track, namely the right track T₁₃. When the head H L reaches a point t₁₂ in the track T₁₁ after a time delay t y from the point t₁₀, the leading head H L picks up the pilot signal f₀ only as cross-talk from the preceding track to the left side of the track T₁₁ and it is thus able at the time t₁₂ to reproduce the cross-talk pilot signal from the preceding track. A tracking error is determined by sensing the difference between the separately detected pilot signal cross-talk components and a tracking control operation is carried out based upon such tracking error signal. Accordingly, the embodiment of the invention illustrated in Figures 3 to 5 is able to produce a tracking error signal by detecting pilot signals recorded in tracks adjacent to a track being scanned as cross-talk with good sensitivity since azimuth loss is avoided, so that the tracking control function can be carried out with high accuracy. The present embodiment also advantageously provides a relatively simple structure for recording and reproducing both NTSC-type signals and high definition video signals by utilizing the same magnetic heads for recording the pilot signal and recording and reproducing the high-definition video signal. It will be appreciated from the foregoing description that the pilot signal recording pattern disclosed herein is but one alternative in that it is possible to record pilot signals in accordance with the present invention in a variety of recording patterns with the use of double azimuth heads. For example, the pilot signal can be recorded by only one of the second set of double azimuth heads in a pattern such that the pilot signals are recorded only in every other track. It will be further appreciated that in place of the second set of double azimuth heads described about in connection with Figure 3, a single magnetic head may be provided at a position spaced by 180° from the first pair of heads for recording the pilot signal. While the embodiment of Figures 3 to 5 has been described for use as a digital video tape recorder, it will be seen that the invention is equally applicable for a variety of recording and reproducing purposes in which recording and reproduction are carried out with the use of rotary heads.

Claims: An apparatus for recording information signals and tracking signals on magnetic tape, the apparatus comprising: first and second magnetic head means (H L , H T ) for recording said information signals on said magnetic tape (11); mounting means for mounting the first and second magnetic head means (H L , H T ) for rotation about an axis for scanning said tape (11) with said first and second magnetic head means (H L , H T ) to record said information signals in successive tracks on said tape (11); said first and second magnetic head means (H L , H T ) being disposed at respective positions along said axis separated from one another by substantially one track pitch and having respectively different azimuth angles; third magnetic head means (H L ′) for recording said tracking signals on said tape (11), said third magnetic head means (H L ′) being mounted by said mounting means at a position rotationally substantially opposite a rotational position of said first magnetic head means (H L ) and substantially axially aligned therewith; and a signal source (20) for supplying said first and second magnetic head means (H L , H T ) with said information signals and said third magnetic head means (H L ′) with said tracking signals. Apparatus according to claim 1 wherein said signal source (20) supplies said information signals in digital form. Apparatus according to claim 1 or claim 2 further comprising fourth magnetic head mean (H T ′) for recording said tracking signals on said tape (11), said fourth magnetic head means (H T ′) being mounted by said mounting means adjacent to said third magnetic head means (H L ′) and having a respective azimuth angle differing from a respective azimuth angle of a said third magnetic head means (H L ′). Apparatus according to claim 3 wherein said signal source (20) is operative in a first mode of operation to supply the third and fourth magnetic head means (H L ′, H T ′) with said tracking signals for recording on said tape (11), and is operative in a second mode of operation to supply said third and fourth magnetic head means (H L ′, H T ′) with said information signals for recording on said tape (11). Apparatus according to claim 4 wherein said signal source (20) is operative in said first recording mode to supply said first and second magnetic head means (H L ′, H T ′) with said information signal in the form of an NTSC signal for recording on said tape (11). Apparatus according to claim 4 wherein said signal source (20) is operative in said second recording mode to supply the first to fourth magnetic head means (H L , H T , H L ′, H T ′) with said information signal in the form of an HDTV signal for recording on said tape (11). Apparatus according to claim 1 wherein the azimuth angle of said third magnetic head means (H L ′) is substantially the same as that of said first magnetic head means (H L ). Apparatus according to claim 3 wherein the azimuth angle of said third magnetic head means (H L ′) is substantially the same as that of said first magnetic head means (H L ) and wherein said fourth magnetic head means (H T ′) is mounted by said mounting means at a position rotationally substantially opposite a rotational position of said second magnetic head means (H T ) and substantially axially aligned therewith, the azimuth angle of said fourth magnetic head means (H T ′) being substantially the same as that of said second magnetic head means (H T ). Apparatus according to claim 8 wherein the signal source (20) is operative to supply said information signal to said first and second magnetic head means (H L , H T ) in the form of an NTSC signal and to supply said tracking signals to said third and fourth magnetic head means (H L ′, H T ′) and wherein the mounting means is operative to rotate the first to fourth magnetic head means (H L , H T , H L ′, H T ′) at a predetermined rotational speed selected with respect to a transport speed of said tape (11) such that the third and fourth magnetic head means (H L ′ H T ′) scan tracks which are one track pitch displaced from tracks last scanned by said first and second magnetic head means (H L , H T ), respectively, such that said information signals and said tracking signals are recorded on respective tracks with different respective azimuth angles. A method of recording information signals and tracking signals on magnetic tape (11), comprising the steps of: recording said information signals in successive tracks on said tape (11) with the use of first and second magnetic head means (H L , H T ) mounted for rotation about an axis at respective axial positions spaced by substantially one track pitch and having respectively different azimuth angles, such that said information signals are recorded with correspondingly different azimuth angles in successive tracks; and recording said tracking signals in at least some of said successive tracks with azimuth angles substantially the same as those of said information signals in adjacent ones of said successive tracks. A method according to claim 10 wherein the step of recording said tracking signals comprises recording said tracking signals with the use of third magnetic head means (H L ′) mounted for rotation at a position rotationally substantially opposite a rotational position of the first magnetic head means (H L ) and substantially axially aligned therewith.

Inventors: YANAGIHARA NAOFUMI PATENTS DIV, YANAGIHARA, NAOFUMI, PATENTS DIVISION
Applicants: SONY CORP, SONY CORPORATION
Application year: 1991
Main classification: H04N5
IPC codes: G11B5, H04N5, G11B15