JP2010182411A - Magnetic tape and servo pattern recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic tape for recording and reproducing data with accuracy and an apparatus for recording servo patterns on the magnetic tape. <P>SOLUTION: The magnetic tape apparatus includes a recording head for recording data between servo patterns on a magnetic tape via a guard space, which are arranged at equal intervals in a longitudinal direction of a data band of the magnetic tape, and a reproducing head for reproducing the data recorded on the magnetic tape and the servo patterns arranged on the data band of the magnetic tape in the width direction of the data band and composed of at least two segments adjacent ones of the segments being formed at different azimuth angles. The magnetic tape apparatus has a detection means for detecting the positioning information of the recording or reproducing head, the deformation information of the magnetic tape and/or the inclination information of the magnetic tape. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a magnetic tape and a servo pattern recording apparatus for the magnetic tape.
About.

  Traditionally, track following servo control examples provide pre-recorded parallel longitudinal servo tracks between longitudinal data tracks, so that one or more servo heads read the servo tracks. And an accompanying track following servo adjusts the position of the head or tape in the tape width direction to maintain the servo head in the desired tape width position relative to the servo track, thereby enabling the data head Is centered with respect to the data track.

  A track following servo system is described in Patent Document 1, for example. This patent document 1 describes a timing-based servo system. Timing-based servo systems are used, for example, with the LTO (Linear Tape Open) format, for example, the IBM LTO Ultimate ™ magnetic tape drive and associated tape cartridges. Is included.

  The linear servo track includes a detectable transition pattern consisting of, for example, pre-recorded magnetic transitions. These transitions form a timing-based servo pattern consisting of a repetitive cyclic sequence of transitions of two different azimuth angle orientations extending in the tape width direction over the linear servo track. For example, this pattern has a transition that is tilted in a first direction relative to the direction of the linear servo track, i.e., having an azimuth angle orientation in the first direction, and an azimuth angle orientation that is tilted in the opposite direction, i.e., in the opposite direction. It may include those with alternating transitions. Thus, as the media moves in a linear direction relative to the servo read head, the position of the servo read head in the tape width direction relative to the timing base servo track causes the time between two transitions having different azimuth angle orientations to be parallel. Perceived based on a scale compared to the time between two transitions having a uniform azimuth angle orientation. The relative timing of transitions read by this servo read head varies linearly with the position of the head in the tape width direction. For this reason, a plurality of parallel data tracks can be aligned with different positions in the tape width direction across the servo tracks (see, for example, Patent Document 1).

US Pat. No. 5,689,384

  In order to increase the surface recording density of the linear magnetic tape device, increasing the linear density has already been studied, so increasing the track density is the most effective. However, it is known that there are the following problems when increasing the track density. That is, how to detect tracking information with high sensitivity, how to cope with the inclination of the running of the magnetic tape with respect to a commonly used 2-bump type head, deformation of the magnetic tape (width direction, longitudinal direction) Direction) and how to reduce head channel spacing.

  In general, a magnetic tape is divided into a plurality (eg, 4) in the width direction, and a data band and a servo band are provided in the width direction of the magnetic tape. When the magnetic tape is shipped, a servo pattern for tracking is recorded in advance in the servo band. When writing data to or reading data from the data band, the servo pattern is reproduced to detect the relative head position information (information at a specific position in the width direction of the magnetic tape from time to time) The playhead is always in the correct position (tracking). For this reason, an additional channel for reproducing the servo pattern is prepared in the head outside the data channel.

  In a linear type magnetic tape apparatus using a two-bump type head, when data is recorded, data is recorded correctly by recording with the upstream bump recording head and then immediately reproducing with the downstream bump reproducing head. (This is called “lead after light” or “lead whistle light”). In the following description, the reproduction head (reproduction channel) indicates a bump on either the upstream (recording side) / downstream (reproduction side) bump unless otherwise specified.

  A two-bump head is a head that has two head blocks that are piggybacked on the playback head (or vice versa) on the recording head. / Playback head, playback / recording (or reverse order) on the second bump, the first bump recording head is the second bump playback head, and the first bump playback The head is aligned with the recording head of the second bump and the track.

  In this way, the cross talk from the recording head to the reproducing head is reduced by separating the recording gap and the reproducing gap from about 1 mm.

  Further, at the time of recording, a reproducing head that is on the same bump as the recording head cannot be used for reproducing servo signals due to crosstalk from the recording head, even though it is a servo channel outside the data channel. Therefore, the servo signal is detected in the servo channel of the reproducing head separated in the traveling direction of the magnetic tape, and the position of the recording head is controlled. If the running of the magnetic tape is tilted in this state, the position of the recording head deviates from the correct position accordingly, and the track density is restricted. In a normal method, in order to reduce the influence of the traveling inclination of the magnetic tape, the distance between the gap line of the first bump and the gap line of the second bump is made closer. It is difficult because there are.

  That is, the tracking operation always tries to align the reproduction gap with the reference track center. Therefore, when the direction (inclination) in which the tape runs in front of the head changes dynamically (tape meandering), the position of the recording gap is an amount corresponding to the tangent of the inclination angle and the distance between the gaps (in the longitudinal direction). Only track deviation (track misregistration) will occur. That is, because the position of the recording track is offset, a part of the recorded adjacent track is overwritten, and the tracking margin is reduced by narrowing the track width. At the time of reproduction, since the data reproduction and servo signal reproduction heads are on the same gap line, this problem (reproduction gap track misregistration) does not occur. Strictly speaking, when the tape travel is tilted, the track misregistration occurs due to the effective change (decrease) in the distance between the tracks of the head. The effect is (1−cosine of the tilt angle) × data bandwidth / 2. In addition, since the reproducing head track <the recording head track width, the influence is small. On the other hand, if it is possible to detect a servo signal by using a reproduction gap in a bump on the recording side during recording, crosstalk from the recording head is difficult because it interferes.

  In view of the circumstances as described above, it is an object of the present invention to provide a magnetic tape capable of accurately recording and reproducing data and a servo pattern recording apparatus for the magnetic tape.

  In order to achieve the above object, a magnetic tape according to the present invention, in a magnetic tape having a data band, and a servo pattern arranged across the entire width of the data band and in the longitudinal direction of the magnetic tape, Data disposed between the servo patterns and a guard space disposed between the servo pattern and the data.

  That is, the present invention provides a magnetic tape having an embedded servo pattern as a magnetic tape that reduces the influence of the inclination of the magnetic tape running that is observed when a two-bump type head is used.

  In the present invention, data is arranged between servo patterns arranged at intervals in the entire width of the data band and in the longitudinal direction of the magnetic tape. In other words, servo patterns, guard spaces, data, guard spaces, servo patterns, guard spaces, data,... Are arranged on a plurality of data bands generally provided in the width direction of the magnetic tape.

  In order to record data in this way, it is assumed that the servo pattern has been recorded in advance, and at the start of recording, usually a plurality of servo patterns are reproduced on the reproduction channel on the same bump as the recording head. No) After the head position is controlled, the recording operation is started. That is, a recording current is supplied to the recording head to record data, and then the recording current is stopped after a certain time has elapsed (immediately before the next servo pattern). The next servo pattern is reproduced again by the reproducing head having the same bump, the head position information is detected, and immediately after that, the recording is resumed. Thereafter, the recording, reproduction and head position control are repeated until the recording is completed. During recording, read after-write (or read-foil write) is performed using a bump reproducing head located downstream. That is, when the recording head is positioned by using a reproducing head on a bump different from the recording head at the time of recording, the position of the recording track shifts and enters into the area of the adjacent track due to tilting of the running of the magnetic tape. In contrast, in the present invention, the recording head and the reproducing head on the same bump are divided in a time-sharing manner. By alternately using it for recording data and detecting the position of the recording head, the servo pattern is reproduced by a reproducing head closer to the recording head (back to back), and this occurs when the tape runs at an angle. It avoids problems and allows data to be recorded in the correct location. Further, the problem of crosstalk from the recording head to the reproducing head can be solved during recording.

  At the time of reproduction, the servo pattern is also reproduced by a reproducing head used for data reproduction (whether the reproducing head on which bump is used depends on the design of the head block) to control the position of the head.

  The data band is an area extending over the entire length of the magnetic tape formed by dividing the magnetic tape in the width direction. The data band is composed of “data subband × number of head channels for performing data recording / reproduction in parallel”. In recording / reproducing data, normally, one data band is ended and then the next data band is started.

  The data subband is an area extending over the entire length of the magnetic tape with channel spacing of a two-bump type head. One channel corresponding to the multi-channel head for parallel recording / reproducing is an area in which scanning is completed by a predetermined number of reciprocations (1 reciprocation = 2 passes) by changing the position in the magnetic tape width direction for each pass.

  Head channel spacing is the distance between the center lines of adjacent channels of a multi-channel head that performs data recording / reproduction in parallel. Not all channels need to be on a single gap line (the gaps may be arranged two-dimensionally or there may be adjacent channels across multiple head blocks).

  The servo pattern spans the entire width of the data band (may be discontinuous) and is composed of a plurality of segments in the width direction. The servo pattern is a combination of magnetization transitions (reversal) used for position control (tracking) of the 2-bump type head in the width direction of the magnetic tape or speed control / phase control of the magnetic tape. The servo patterns are arranged at intervals in the longitudinal direction of the magnetic tape. The servo pattern is recorded in advance on the magnetic tape when the magnetic tape is shipped, and is not rewritten by individual magnetic tape devices. The segment boundaries are virtual lines (lines in the longitudinal direction of the magnetic tape) connecting the azimuth angle change points.

  The guard space is an area (gap) that separates the servo pattern and the data burst (data). It plays the role of absorbing fluctuations in the longitudinal position of the magnetic tape of the data burst that occur during data recording. Necessary for formatting.

  The servo pattern is first recorded on the magnetic tape by a servo pattern recording head having a recording gap of the same shape as the boundary shape of the magnetization transition, and then a part of the recorded servo pattern is recorded by a subsequent full width erasing head. You may form by erasing so that a recording part may be formed. The magnetization transition includes inversion. The boundary is in the recording surface of the magnetic tape, and the magnetization transition (reversal) is based on the change in recording current.

  As a result, a servo pattern having a short length in the traveling direction can be formed.

It is preferable that the servo pattern is formed of at least two segments in the width direction of the data band on the data band, and adjacent segments are recorded with different azimuth angles. (Number of segments> = number of azimuth angles)
Thereby, in addition to magnetic head positioning information (tracking information) magnetic tape speed information, magnetic tape deformation (width and longitudinal expansion / contraction) information and tape tilt information can be detected by the magnetic tape device. .

  As the azimuth angle given to each segment of the servo pattern, at least two of the positive, negative, and 0 degrees having the same absolute value may be used.

  Thereby, in addition to magnetic head positioning information (tracking information) magnetic tape speed information, magnetic tape deformation (width and longitudinal expansion / contraction) information and tape tilt information can be detected by the magnetic tape device. .

  The servo patterns are preferably arranged at equal intervals in the longitudinal direction of the magnetic tape.

  Thereby, servo information can be periodically provided by the magnetic tape. At the same time, it facilitates tape speed control.

  The width of each segment of the servo pattern constituted by at least two segments in the width direction of the data band may be set to be approximately an integral multiple of the track pitch of the data track on which the data is recorded.

  As a result, the servo pattern extends over a plurality of data tracks in the width direction of the data band.

  When there are a plurality of the data bands in the width direction of the magnetic tape, the longitudinal positions of the servo patterns are made to be the same between adjacent data bands, and the azimuth angle of the magnetization transition that forms the servo pattern is set. An azimuth angle with a different sign may be used between segments sandwiching a virtual boundary line between adjacent data bands. The magnetization transition includes reversal, and the azimuth angle may be set to 0 degree between the segments across the virtual boundary line of the data band.

  Alternatively, when there are a plurality of the data bands in the width direction of the magnetic tape, the positions of the servo patterns in the longitudinal direction are made substantially the same between the adjacent data bands, and the transition of magnetization forming the servo pattern is performed. The azimuth angle may be the same as the azimuth angle between the segments across the virtual boundary line between adjacent data bands. The magnetization transition includes reversal, and the azimuth angle may be set to 0 degree between the segments across the virtual boundary line of the data band.

  Thus, the magnetic head positioning information, the magnetic tape deformation information and / or the magnetic tape tilt information can be detected by the magnetic tape device. The latter is also effective for expanding the dynamic range of head positioning information.

  When recording the full width of the magnetic tape with the servo pattern full width recording head having a recording gap of the same shape as the boundary shape of the magnetization transition of the servo pattern, the change of the recording current per servo pattern (including reversal) The number of times may be all odd or all even. The magnetization transition includes inversion. The boundary is in the recording surface of the magnetic tape, and the magnetization transition (reversal) is based on the change in recording current.

  Thereby, it is possible to select that the initial magnetization state (direction) of the data recording area (data burst recording area) sandwiched between the servo patterns is reversed or the same before and after the servo pattern. That is, the initial magnetization states (directions) of a large number of data recording areas formed on the magnetic tape (before the first data recording by the magnetic tape device) can be reversed or all the same.

  When recording the full width of the magnetic tape with a servo pattern full width recording head having a recording gap of the same shape as the boundary shape of the magnetization transition of the servo pattern, binary data or unique synchronization is modulated by modulating the timing of change of the recording current. A signal may be expressed. The magnetization transition includes inversion. The boundary is in the recording surface of the magnetic tape, and the magnetization transition (reversal) is based on the change in recording current.

  As a result, binary data or a unique synchronization signal can be expressed by modulating the timing of change (including inversion) of the recording current.

  The servo pattern is first recorded on the magnetic tape by a servo pattern recording head having a recording gap of the same shape as the boundary shape of the magnetization transition, and then a part of the recorded servo pattern is recorded by a subsequent full width erasing head. When erasing to form a recording portion, the modulation of the recording current and the operation timing of the subsequent full-width erasing head are controlled so that binary data is expressed in the servo pattern, or a unique synchronizing signal is generated. You may make it express. The magnetization transition includes inversion. The boundary is in the recording surface of the magnetic tape.

  As a result, the modulation of the recording current and the operation timing of the subsequent full-width erasing head can be controlled to express binary data or a unique synchronization signal in the servo pattern.

  The servo pattern may correspond to 1-bit data, or may correspond to a unique sync signal.

  Thereby, 1-bit data or a unique synchronization signal can be provided by the servo pattern.

  When inserting the address information into the servo pattern, the servo pattern in which the unique synchronization signal is inserted precedes the servo pattern in which the address information is inserted, thereby ensuring frame synchronization of the address information. I can do it.

  When address information is inserted into the servo pattern, a modulo address generator that is sufficiently longer than the longest magnetic tape that can be handled by the servo pattern recording device is used, and a raw magnetic tape is loaded into the servo pattern recording device. It may be manufactured by using a servo pattern recording device adapted to reset the address of the address generator every time. Raw magnetic tape includes unrecorded magnetic tape.

  Thereby, address information can be recorded on the magnetic tape.

  A magnetic tape device according to the present invention is a magnetic tape having a data band, the servo tape having a servo pattern disposed across the entire width of the data band and in the longitudinal direction of the magnetic tape. A recording head for recording data between the servo patterns through a guard space between the servo patterns and a reproducing head for reproducing the data recorded on the magnetic tape are provided.

  In the present invention, servo patterns, guard spaces, data, guard spaces, servo patterns, guard spaces, data,... Are arranged on a plurality of data bands generally provided in the width direction of the magnetic tape.

  In order to record data in this way, it is assumed that the servo pattern has been recorded in advance, and at the start of recording, usually a plurality of servo patterns are reproduced on the reproduction channel on the same bump as the recording head. No) After the head position is controlled, the recording operation is started. That is, a recording current is supplied to the recording head to record data, and then the recording current is stopped after a certain time has elapsed (immediately before the next servo pattern). The next servo pattern is reproduced again by the reproducing head having the same bump, the head position information is detected, and immediately after that, the recording is resumed. Thereafter, the recording, reproduction and head position control are repeated until the recording is completed. During recording, read after-write (or read-foil write) is performed using a bump reproducing head located downstream. That is, when the recording head is positioned by using a reproducing head on a bump different from the recording head at the time of recording, the position of the recording track shifts and enters into the area of the adjacent track due to tilting of the running of the magnetic tape. In contrast, in the present invention, the recording head and the reproducing head on the same bump are divided in a time-sharing manner. By alternately using it for recording data and detecting the position of the recording head, the servo pattern is reproduced by a reproducing head closer to the recording head (back to back), and this occurs when the tape runs at an angle. It avoids problems and allows data to be recorded in the correct location. Further, the problem of crosstalk from the recording head to the reproducing head can be solved during recording.

  At the time of reproduction, the servo pattern is also reproduced by a reproducing head used for data reproduction (whether the reproducing head on which bump is used depends on the design of the head block) to control the position of the head.

  Thus, in addition to magnetic head positioning information (tracking information) magnetic tape speed information, magnetic tape deformation (width and longitudinal expansion / contraction) information and tape tilt information can be detected by the magnetic tape device. .

  For reproduction of the servo pattern, at least two channels of data channels of the reproduction head are used. From the correlation between reproduction servo signals from each channel, magnetic tape speed information, and reproduction head channel information, Positioning information of the recording head or the reproducing head, deformation information of the magnetic tape, and / or tilt information of the magnetic tape may be detected.

  Thereby, the positioning information of the recording head or the reproducing head, the deformation information of the magnetic tape, and / or the tilt information of the magnetic tape can be detected.

  For reproduction of the servo pattern, at least two channels are used among the data channel and servo auxiliary channel of the reproduction head, the correlation between reproduction servo signals from each channel, magnetic tape speed information, and reproduction head The recording head or reproducing head positioning information, magnetic tape deformation information, and / or magnetic tape tilt information may be detected from the channel information.

  Thereby, the head positioning information of the recording head or the reproducing head, the deformation information of the magnetic tape, and / or the tilt information of the magnetic tape can be detected. At the same time, it is effective for expanding the dynamic range of head positioning information detection.

  Segments of different azimuth angles of the servo pattern are reproduced on the corresponding reproduction channels, and the elapsed time between the respective output signals or the time difference measured by the clock in the magnetic tape device, the magnetic tape speed information and Further, positioning information in the track width direction of the recording head or the reproducing head may be obtained by combining a reference value determined in advance for each combination of the corresponding reproducing channels.

  Thereby, positioning information in the track width direction of the recording head or the reproducing head can be obtained.

  A segment having a positive azimuth angle and a segment having a negative azimuth angle of the servo pattern may be reproduced by corresponding reproduction channels.

  As a result, the information on the positive azimuth angle segment and the negative azimuth angle segment of the servo pattern can be reproduced on the corresponding reproduction channels.

  First information regarding a position obtained from a combination of positive and negative first azimuth angles of the servo pattern and a position obtained from a combination of second azimuth angles having a positive and negative value larger than the first azimuth angle. The positioning information may be obtained by combining the second information. The first information is, for example, low sensitivity and wide dynamic range information regarding the position, and the second information is, for example, high sensitivity and narrow dynamic range information regarding the position.

  Thereby, rough adjustment of the head position is performed using low-sensitivity information, and then precise head positioning (tracking) is enabled using high-sensitivity information. That is, the contradictory conditions of high sensitivity and wide dynamic range can be satisfied.

  A segment in which the azimuth angle of the servo pattern is not 0 degree is reproduced by two corresponding reproduction channels, and a first value which is an elapsed time between reproduction signals or a time difference measured by a clock in the magnetic tape device By combining the second value obtained by reproducing the segment having the azimuth angle opposite to this with the corresponding second two reproduction channels, the magnetic tape speed information, and the reproduction head channel information, the magnetic tape The deformation information and / or the tilt information of the magnetic tape may be detected.

  Thereby, deformation information of the magnetic tape and / or tilt information of the magnetic tape can be detected.

  A segment having an azimuth angle of 0 degrees of the servo pattern is reproduced on the corresponding two reproduction channels, the elapsed time between reproduction signals or the time difference measured with the clock in the apparatus, the magnetic tape speed information, the reproduction head The tilt information of the magnetic tape may be detected in combination with the channel information.

  Thereby, the inclination information of the magnetic tape can be detected.

  The first two segments of the servo pattern having equal azimuth angles other than 0 degrees are reproduced by the first reproduction channel pair, and the elapsed time between the reproduction signals or the time measured by the clock in the magnetic tape device The second two segments with the same azimuth angle, which are the opposite, are reproduced on the second reproduction channel pair to obtain the elapsed time or time difference between the reproduction signals, and the tape speed information and the reproduction are obtained. Magnetic tape detected by combining the head channel information and detecting the mixed information of the deformation information and the tilt information of the magnetic tape and reproducing the segment having the azimuth angle of 0 degree by the third reproduction channel pair Magnetic tape deformation information may be obtained using the tilt information.

  Thereby, magnetic tape deformation information can be obtained using the tilt information of the magnetic tape.

  The elapsed time or the measurement time difference between the output signals may be detected as a phase difference by a burst phase comparator.

  Thereby, the phase difference (that is, the time information) can be detected by the burst phase comparator.

  The positioning information in the track width direction of the recording head or the reproducing head may be corrected using the deformation information and / or the tilt information of the magnetic tape.

  Thereby, the recording head and / or the reproducing head can be positioned at a more accurate position in the track width direction.

  The tilt angle of the recording head or the reproducing head may be controlled according to the tilt information of the magnetic tape. The tilt angle includes the azimuth angle.

  Thereby, the recording head and / or the reproducing head can be positioned at a more accurate position.

  The magnetic tape speed information may be set as speed information (target value) that has been set, and / or the magnetic tape speed information may be obtained by measuring the period of a servo pattern to be reproduced. The set speed information includes information on the target value of speed.

  Thereby, the magnetic tape speed can be obtained.

  When there is a segment having an azimuth angle of 0 degrees in the servo pattern, the speed information may be obtained by measuring the period of the servo pattern output from the channel for reproducing the segment.

  Thereby, accurate speed information can be obtained.

  If there is no segment with an azimuth angle of 0 degrees in the servo pattern, the period of the servo pattern output from the playback channel corresponding to the positive segment of the azimuth angle and the servo pattern output from the playback channel corresponding to the negative segment It is good also as speed information by measuring a period and performing the calculation which considered the absolute value of each azimuth angle.

α1 and α2 are the (known) azimuth angles of the servo pattern, and the tape is raised by Δd while the tape is running from the (n−1) th servo pattern to the nth servo pattern (relative to the head). Down)
Δd1 (˜dn−dn−1), dn−1, dn: n−1, position of head at n (calculated value)
T1 = T01 + Δd1tan (−α1 + Δγ1), T1: Time from n−1 to n (actual measurement value)
T01 = T1 + Δd1tan (α1−Δγ1), T01: period obtained from T1 Δγ1 = arctan (Δd1 / T01) << α1
Therefore, T01 = T1 + Δd1tanα1
Similarly, T02 = T2-Δd2tan α2
T0 = (T01 + T02) / 2, T0: estimation period T0 = ((T1 + T2) / 2) + Δd1 tan α1−Δd2 tan α2
Since the servo patterns with positive and negative azimuth angles are substantially at the same position in the longitudinal direction on the tape, Δd1 = Δd2 = Δd
Therefore, T0 = ((T1 + T2) / 2) + Δd (tan α1-tan α2)
When considering the deformation of the tape, α1 and α2 may be (α1−β) and (α2−β) (see, for example, FIG. 18).

  Thus, speed information can be obtained even when there is no segment having an azimuth angle of 0 degrees in the servo pattern.

  A segment having an azimuth angle of 0 degrees in the servo pattern is sequentially reproduced by the reproducing head for the upstream bump and the reproducing head for the downstream bump of the magnetic tape running, and the elapsed time or the measurement time difference between the two reproducing heads. Magnetic tape speed information may be obtained using the gap distance.

  Thus, the magnetic tape speed information can be obtained using the upstream reproducing head and the downstream reproducing head of the magnetic tape running.

  Each of the positive and negative azimuth angle segments of the servo pattern is sequentially reproduced by the upstream reproducing head and the downstream reproducing head, and the difference between the elapsed time or the measurement time and the gap distance between the upstream and downstream reproducing heads. After obtaining the first speed information and the second speed information, calculation may be performed in consideration of channel information of the used reproducing head and azimuth angle information to obtain speed information.

  Thus, each of the positive and negative azimuth angle segments can be sequentially reproduced by the upstream reproducing head and the downstream reproducing head to obtain speed information.

  When the magnetic tape is phase-locked, if there is a segment with an azimuth angle of 0 degrees in the servo pattern, the period of the output servo pattern of the channel that reproduces the segment is divided as necessary to obtain a reference signal And phase comparison.

  As is well known, the phase detector is +/− 90 degrees for the simplest multiplication type and +/− 180 degrees for the more elaborate type, and the limit of exterior detection, beyond which the next transition and The result of phase comparison is output. That is, if there is a difference in the frequency of the reference signal and VFO (variable frequency transmitter), a 1: 1 phase comparison between the two transitions cannot be performed, and the frequency component of the difference between the two frequencies is dominant in the output of the detector. become. The problem when the phase loop is formed is whether or not the VFO has good responsiveness and responds quickly to the above-described frequency component to be synchronized. A VFO with a mechanical system such as a tape running system is slow to respond. On the other hand, if the phase comparison frequency is lowered (divided), the absolute value of the time window corresponding to +/− 90 degrees or +/− 180 degrees is increased. As a result, it becomes easier to enter synchronization at a certain point. However, since the phase synchronization system is also a sampling system, it is desirable that the frequency of phase comparison is high from the viewpoint of sampling. Therefore, the degree of frequency division is determined in consideration of the synchronization pull-in and the accuracy after synchronization.

  This makes it possible to phase-lock the magnetic tape when there is a segment with an azimuth angle of 0 degrees in the servo pattern.

When the magnetic tape is phase-locked, if there is no segment with an azimuth angle of 0 degrees in the servo pattern, the period of the output servo pattern of the reproduction channel corresponding to the segment with a positive azimuth angle is divided by a predetermined frequency. Divide as many times as necessary by the ratio and compare the phase with the first reference signal, and divide the period of the output servo pattern of the playback channel corresponding to the negative segment by the same division ratio to the second The phase may be compared with the reference signal, and the output of each phase comparator may be phase-locked by performing an operation considering the absolute value of the azimuth angle. The second reference signal may be substantially the same (frequency) as the first reference signal. On the other hand, when the output of the channel of the positive azimuth angle and the output of the channel of the negative azimuth angle are greatly different, the first reference signal and the second reference signal are signals having the same frequency and different phases.
Assuming that α1 and α2 are the (known) azimuth angles of the servo pattern, and the tape has moved up by d (relatively lowering the head) while the tape traveled by ΔT,
[Delta] T _- the distance between the segment and the REF of the azimuth angle [alpha] 1 (reference) (or period)
Distance (or period) between the segment of ΔT ₊ azimuth angle α2 and REF (reference)
ΔT = (ΔT ₋ + ΔT ₊ ) / 2 + d (tan α1−tan α2)
When considering the deformation of the tape, α1 is set to (α1-γ), (α1-β-γ), and α2 is set to (α2 + γ), (α2-β + γ) (see, for example, FIG. 19). ).

  This makes it possible to lock the phase of the magnetic tape when there is no segment with an azimuth angle of 0 degrees in the servo pattern.

  At the time of the data recording, the servo pattern may be reproduced using a reproducing head piggybacked on the upstream recording head.

  Thus, data can be recorded by the upstream bump recording head, and the servo pattern can be reproduced by the upstream bump reproducing head.

  At the time of data reproduction, the servo pattern may be reproduced using the downstream reproduction head.

  As a result, the servo pattern can be reproduced using the downstream reproducing head during data reproduction.

  At the time of the data recording, the servo pattern may be reproduced using the reproduction head downstream. At this time, the head positioning is offset according to the detected tape inclination and the distance between the recording gap and the reproduction gap in the longitudinal direction.

  Thereby, the servo pattern can be reproduced by using the downstream reproducing head at the time of data recording.

  During the data reproduction, the servo pattern may be reproduced using a reproducing head piggybacked on the upstream recording head. At this time, the head positioning is offset according to the detected tape inclination and the distance between the recording gap and the reproduction gap in the longitudinal direction.

  Thereby, at the time of data reproduction, the servo pattern can be reproduced by using the reproducing head piggybacked on the upstream recording head.

  Information on the deviation of the recording and / or reproducing gap individual positions of the recording head and the reproducing head from a reference position is stored in the magnetic tape device, and the recording head and the reproducing are used using the information. Head position information, magnetic tape deformation information, magnetic tape tilt information, magnetic tape speed information, and / or magnetic tape phase information are corrected.

  Thereby, position information of the recording head and the reproducing head, deformation information of the magnetic tape, tilt information of the magnetic tape, magnetic tape speed information, and / or phase information of the magnetic tape can be corrected.

  The data band and / or path identification information may be inserted at a predetermined position in the area for each path, which is a component of the data area sandwiched between the servo patterns.

  As a result, the identification information of the data band and / or the path can be identified at a predetermined position in the data area by the magnetic tape device.

  For each pass, an integer multiple of the data area sandwiched between the servo patterns, the adjacent preceding or succeeding servo pattern, and the accompanying guard space may be handled as physical blocks. .

  The data burst includes one-pass partial data in a region sandwiched between servo patterns on the data band. In each area, data bursts of a prescribed number of passes (2 × number of reciprocations) are multiplexed in the magnetic tape width direction (multiplexed by changing track positions for each pass).

  This facilitates data management.

  For each pass, one or a plurality of data areas sandwiched between the servo patterns, adjacent preceding or succeeding servo patterns, and accompanying guard spaces are used as tape marks. May be. The tape mark includes a file mark. The tape mark (file mark) represents the end of data.

  This facilitates handling of the magnetic tape.

  A servo pattern recording apparatus according to the present invention comprises a recording head having a recording gap having the same shape as the boundary of magnetization transition of a servo pattern recorded on a magnetic tape, and recording the servo pattern over the entire width of the magnetic tape; And a control means for controlling the number of changes in the recording current per servo pattern to all odd numbers or all even numbers when recording the full width of the magnetic tape by the recording head. The magnetization transition includes inversion. The boundary is in the recording surface of the magnetic tape, and the magnetization transition (reversal) is based on the change in recording current.

  In the present invention, the servo pattern can be recorded on the full width of the magnetic tape by the servo pattern full-width recording head with the number of changes (including reversal) of the recording current all odd or even by the control means.

  A servo pattern recording apparatus according to the present invention includes a magnetic head having a recording gap having the same shape as the boundary of magnetization transition of a servo pattern recorded on a magnetic tape, and recording the servo pattern over the entire width of the magnetic tape. First, recording is performed on the magnetic tape by the recording head, and then the servo pattern is formed by erasing a part of the servo pattern by the subsequent full-width erasing head so as to form a data recording area.

  As a result, a servo pattern having a narrow width (length) in the running direction of the magnetic tape or a servo pattern having a short length in the running direction of the magnetic tape can be formed.

  When recording the full width of the magnetic tape with the recording head, the servo pattern may be expressed as binary data or a unique synchronization signal by modulating the change timing of the recording current. The magnetization transition (inversion) is based on a change in recording current.

  As a result, binary data or a unique synchronization signal can be expressed by modulating the timing of change (including inversion) of the recording current.

  When the servo pattern is first recorded on the tape by the recording head and then a part of the recorded servo pattern is erased so as to form a data recording portion by the subsequent full width erasing head, The operation timing of the subsequent full width erasing head may be controlled to express binary data in the servo pattern or to express a unique synchronization signal.

  As a result, the modulation of the recording current and the operation timing of the subsequent full-width erasing head can be controlled to express binary data or a unique synchronization signal in the servo pattern.

  The servo pattern may correspond to 1-bit data, or may correspond to 1-bit data or a unique synchronization signal.

  Accordingly, 1-bit data, 1-bit data, or a unique synchronization signal can be provided by the servo pattern.

  When address information is inserted into the servo pattern, a modulo address generator that is sufficiently longer than the longest magnetic tape that can be handled by the servo pattern recording device is used, and a raw magnetic tape is loaded into the servo pattern recording device. Each time the address generator address is reset. In addition, when inserting the address information into the servo pattern, the servo pattern in which the unique synchronization signal is inserted is preceded by the servo pattern in which the address information is inserted, thereby synchronizing the frame of the address information. I can do it for sure.

  Thereby, address information can be recorded on the servo pattern.

  The servo pattern recording device includes a tape traveling device that travels an unrecorded magnetic tape at a constant speed, a recording head that is in contact with the tape, and an electronic circuit that supplies current to the recording head. The servo pattern recording operation is merely changing the recording current while the magnetic tape is running at a constant speed (generally, the current flows at a point other than the transition).

  The recording method according to the present invention is a method for recording data on a magnetic tape having a data band, wherein servo signals are generated from servo patterns arranged at intervals in the entire width of the data band and in the longitudinal direction of the magnetic tape. And recording data via the guard space between the servo patterns based on the acquired servo signal.

  The servo pattern is recorded on the tape with the servo pattern recording head having the same recording gap as the shape of the boundary of the magnetization transition so that the number of transitions is odd or even number per servo pattern. By doing so, a data recording area may be formed.

  The servo pattern is first recorded on the magnetic tape by a servo pattern recording head having a recording gap of the same shape as the boundary shape of the magnetization transition, and then a part of the recorded servo pattern is recorded by a full width erasing head downstream. The data recording area may be formed by erasing.

  On the data band, the servo pattern is composed of at least two segments in the width direction of the data band, and adjacent segments are recorded at different azimuth angles to form a data recording area. May be.

  As described above, according to the present invention, a magnetic tape capable of accurately recording and reproducing data, a servo pattern recording device for the magnetic tape, and deformation (width and longitudinal expansion / contraction) information of the magnetic tape. And a magnetic tape device capable of detecting tilt information of the magnetic tape, a method for manufacturing the magnetic tape, and a recording method can be provided.

It is a top view which shows the magnetic tape which concerns on one Embodiment of this invention. It is a top view which shows the example of the servo pattern of the magnetic tape shown in FIG. It is a principle explanatory view of detection of information on a head position of a magnetic tape device, magnetic tape deformation, and magnetic tape tilt. It is a principle explanatory view of detection of information on a head position of a magnetic tape device, magnetic tape deformation, and magnetic tape tilt. It is a principle explanatory view of detection of information on a head position of a magnetic tape device, magnetic tape deformation, and magnetic tape tilt. It is structure explanatory drawing of an example (2d) of a servo pattern. It is a principle explanatory view of detection of information on a head position of a magnetic tape device, magnetic tape deformation, and magnetic tape tilt. It is a partial plan view of a conventional magnetic tape device head and a conventional magnetic tape. It is explanatory drawing of the shift | offset | difference of a recording track when the conventional magnetic tape running inclines. It is a figure which shows the positional relationship of the servo pattern and data band of one Example, and the relationship between a head channel position and a path | pass. It is a block diagram of a tracking servo mechanism of a magnetic tape device. It is a block diagram which shows the detail of the peak detection / time measuring device of a tracking servo mechanism. It is a block diagram which shows the detail of the tracking (LTM) detector of a tracking servo mechanism. FIG. 6 is a block diagram illustrating details of another tracking (LTM) detector. FIG. 15A shows a magnetization pattern on the magnetic tape, FIG. 15B shows a current waveform for recording the magnetization pattern, and FIG. 15C modulates a servo pattern composed of four transitions to generate 1-bit address or data, or An example representing a unique sync (synchronization) pattern 1 or 2 is shown. FIGS. 16A and 16B are images on a magnetic tape. As an example, both extreme examples of the frame configuration when a 20-bit address and 128-bit management data (128 bits may be data + error control bits) are inserted. Show. FIG. 16B is a configuration example of a servo pattern recording apparatus having the frame configuration shown in FIG. 16B. FIG. It is a principle explanatory drawing which detects the period (speed information) of a magnetic tape which has a servo pattern of positive and negative azimuth angles. It is a principle explanatory view when locking the phase of a magnetic tape having a servo pattern with positive and negative azimuth angles.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing a magnetic tape according to an embodiment of the present invention, FIGS. 2A to 2D are plan views showing examples of servo patterns 2 of the magnetic tape 1 shown in FIG. 1, and FIG. FIG. 3 is a diagram for explaining the principle of detecting information on the head position of the tape device, the deformation of the magnetic tape 1 and the tilt of the magnetic tape 1.
As shown in FIG. 1, the magnetic tape 1 includes a plurality of (for example, four) data bands b0, b1, b2, and b3 and the entire width of the data bands b0, b1, b2, and b3, and the magnetic tape 1 Servo pattern 2 arranged at intervals in the longitudinal direction, data burst 3 arranged between servo pattern 2 and servo pattern 2, and guard space arranged between servo pattern 2 and data burst 3 4 is provided. For example, an integral multiple of servo pattern 2, data burst 3, and guard space is handled as a physical block.

  The data bands b0, b1, b2, and b3 are regions extending over the entire length of the magnetic tape 1 formed by dividing the magnetic tape 1 in the width direction. Each of the data bands b0, b1, b2, and b3 is composed of “data subband × the number of channels of the head of the magnetic tape device that performs data recording / reproduction in parallel”. In recording / reproducing data, normally, one data band is ended and then the next data band is started.

  The data subband is an area extending over the entire length of the magnetic tape 1 by channel spacing of the head H. One channel corresponding to the multi-channel head for parallel recording / reproducing is an area where the position is changed in the width direction of the magnetic tape 1 for each pass, and scanning is completed by a prescribed number of reciprocations (one reciprocation = 2 passes). .

  The head channel spacing is a distance between the center lines of adjacent channels of a multi-channel head H that performs data recording / reproduction in parallel. Not all channels need to be on a single gap line (two-dimensional gaps may be arranged, or each of a plurality of head blocks HB1, HB2, HB3... Constituting the head. May have channels).

  The servo pattern 2 is arranged over the entire width of the data bands b0, b1, b2, and b3 (may be discontinuous) and at intervals in the longitudinal direction of the magnetic tape 1. Note that the servo pattern 2 of the data band b0 and the servo pattern 2 of the data band b1 may be arranged shifted (offset) in the longitudinal direction of the magnetic tape 1. The numbering method of the data bands b0 to b3 is not limited to this.

  The servo pattern 2 is a combination of magnetization reversal used to control the position of the head H in the width direction of the magnetic tape 1 (take tracking), or to control the speed / phase of the magnetic tape 1. The servo pattern 2 is recorded in advance when the magnetic tape 1 is shipped, and is not rewritten by individual magnetic tape devices. The servo patterns 2 are arranged, for example, at equal intervals in the longitudinal direction of the magnetic tape 1.

  The data burst 3 includes partial data of a specified number of passes (2 × number of reciprocations) in the area sandwiched between the servo pattern 2 and the servo pattern 2 on the data bands b0, b1, b2, and b3. In each area of the data burst 3, partial data having a prescribed number of passes (2 × number of reciprocations) is multiplexed in the width direction of the magnetic tape 1 (multiplexed by changing the track position for each pass).

  The guard space 4 is a region (gap) that separates the servo pattern 2 and the data burst 3. It plays a role of absorbing fluctuations in the longitudinal position of the magnetic tape of the data burst 3 that occur during data recording. Necessary for formatting.

  The servo patterns 2a, 2b, and 2c shown in FIGS. 2A, 2B, and 2C are each composed of two segments in the width direction of the data band b0. For example, the servo pattern 2a is formed of two segments s1 and s2 formed at a predetermined positive and negative azimuth angle with respect to a direction orthogonal to the traveling direction of the magnetic tape 1. As shown in FIG. 2A, for example, the azimuth angles of the segments s1 and s2 forming the servo pattern 2a have different signs across the virtual boundary line G between the data band b0 and the data band b2. Yes. As shown in FIG. 2B, for example, the azimuth angle of each segment forming the servo pattern 2b has the same sign across the virtual boundary line G between the data band b0 and the data band b2. . The width of each segment s1, s2 of the servo pattern 2a is substantially an integral multiple of the track pitch of the data track on which data is recorded.

  FIG. 2C shows an example in which a servo pattern 2c is once recorded at a predetermined length, and then a part 2c ′ of the servo pattern 2c is partially erased by a subsequent erase head to form a data area. ing.

  In FIG. 2D, the servo pattern 2d is composed of six segments. The (recording) azimuth angle of each segment of the servo pattern 2d is set to positive, negative, and 0 degrees having the same absolute value.

  In these examples, the servo patterns 2a, 2b, 2c and 2d are continuously arranged in the width direction of the magnetic tape 1, but are discontinuous at the boundary between the adjacent data band b0 and the data band b2, for example. It may be.

  As shown in FIG. 3, when the servo pattern 2b is composed of equal positive and negative azimuth angle α segments, positional information (deviation) in the track width direction (Y direction) of the head H of the magnetic tape device described later. The principle of detecting the amount d), the deformation information (angle β) of the magnetic tape 1 and the tilt information (angle γ) of the magnetic tape 1 will be described. Assuming that the channels A, B, C, and D of the head H are on the same gap line GL, consider the time when the head H of the magnetic tape device outputs a signal in response to the magnetization reversal of the servo pattern 2b.

  The two-bump type head H is a single head H in which the head blocks HB1 and HB2 in which the reproducing head H2 is piggybacked on the recording head H1 (or vice versa) are aligned in the opposite direction. The recording / reproducing heads H1, H2 and the head block HB2 (second bump (downstream bump) constituting) are reproduced / reproduced on the head block HB1 (first bump (upstream bump)). The recording heads H2 and H1 are arranged (or in the reverse order), the first bump recording head H1 is the second bump reproducing head H2, and the first bump reproducing head H2 is the second bump reproducing head H2. The bump recording head H1 is aligned with the track position.

  As shown in FIG. 3, when the magnetic tape 1 is raised by the length d (relatively the head H is lowered) due to LTM (movement in the width direction of the running magnetic tape 1), the channels A and C The phase of the output advances by the same value (the output time point is advanced), and the output of channels B and D is delayed by the same value (the output time point is delayed).

  LTM is an abbreviation for lateral tape motion, and is a movement in the width direction of the magnetic tape 1 that occurs when the magnetic tape 1 travels. This is a factor that hinders the tracking of narrow pitch tracks (and therefore narrow tracks). The servo pattern 2b is reproduced, the relative position between the head H and the magnetic tape 1 is detected, and the LTM is tracked so that the head H is placed at the correct track position as much as possible (tracking servo).

  When the magnetic tape 1 is deformed (an example in which the width of the magnetic tape 1 is widened (the angle formed by the positive and negative segments is increased by an angle 2β) and the length is shortened), the channels A, B, C, and D are all The phase of the output is delayed, but the amount of delay is small for channels A and B and large for channels C and D.

  When the magnetic tape 1 travels at an angle γ with respect to the Y direction, the output phases of the channels A and C advance and the channels B and D deviate. The direction of phase change of channels A, B, C, and D is the same as in LTM, but the amount of change is small for channels A and B and large for channels C and D. These are represented by the direction and length of the arrow in FIG. As described above, the effects of the LTM, the deformation of the magnetic tape 1 and the inclination of the traveling of the magnetic tape 1 are all different. However, even when they are mixed, they can be completely separated as shown below.

FIG. 4 is a diagram for explaining the principle of detection of information on the head position of the magnetic tape device, the deformation of the magnetic tape 1 and the tilt of the magnetic tape 1.
On the magnetic tape 1 having the servo pattern 2b, a shift d (positioning information) due to LTM (movement in the width direction of the running magnetic tape 1), an azimuth angle change due to deformation is ± β (deformation information), an inclination γ (inclination information) ) Occurs in combination. The shift d becomes positioning information of the head H (or the magnetic tape 1). As shown in FIG. 4, the intersections of the channels A, B, C and D and the servo pattern 2b indicated by the dotted line in the normal state are (xA, yA), (xB, yB), (xC, yC), Let D (xD, yD) be the intersection of the servo pattern 2b indicated by the solid line affected by the shift, deformation, and tilt, (x'A, yA), (x'B, yB), (x'C, yC) ), (X′D, yD). Further, the coordinates of the apex of the servo pattern 2b in the normal state are (0, 0), the apex angle is (π-2α), that is, the azimuth angle ± α, and the shift amount is d. Of the unknown numbers (d, γ, β), for example, d is obtained as follows.

by the way,
x′A−x′B = V × t′AB = V (t′B−t′A)
x′C−x′A = V × t′CA = V (t′A−t′C)
x′D−x′B = V × t′DB = V (t′B−t′D)
here,
V: Magnetic tape speed t'AB, t'CA, t'DB: Elapsed time between detection outputs t'A, t'B, t'C, t'D: Output detection times of channels A to D yA, yB , YC, yD: positions of channels (heads H) A to D in the magnetic tape width direction (reference values predetermined for each combination of known reproduction channels: channel information (coordinate information))
Here, the positions yA, yB, yC, yD and the azimuth angle α in the y-axis direction of each channel A to D are known, and for example, the points (x′A, yA) and (x′B, yB) The distance in the x-axis direction is the elapsed time or time difference between the outputs of the corresponding channels A and B (both measured values): t′B−t′A multiplied by the magnetic tape speed V.

  That is, K1 and K2 are obtained from the known value and the measured value, and as a result, d is obtained.

In this case, both the denominator and numerator of the equation for obtaining d are in the form of a coefficient multiple of V, and d can be obtained from y and t regardless of V. β and γ can also be obtained.
Next, a case will be described in which the magnetic tape 1 having the servo pattern 2e has a shift d due to LTM, and an azimuth angle change due to deformation is combined with ± β and inclination γ. The servo pattern 2e shown in FIG. 5 is composed of segments having equal positive and negative azimuth angles ± α and two segments having an azimuth angle of 0 degrees. At this time, the principle of detecting the position information (shift d) of the head H in the track width direction and the tilt information (angle γ) of the magnetic tape 1 will be described (assuming β = 0).

FIG. 5 is a diagram for explaining the principle of detection of information on head position, magnetic tape deformation and magnetic tape tilt.
As shown in FIG. 5, when the channels A, B, C, and D of the head H are on the same gap line GL, the head H of the magnetic head device outputs a signal in response to the magnetization reversal of the servo pattern 2e. think of.

  As shown in FIG. 5, the case where the magnetic tape 1 having the servo pattern 2e is lifted by LTM (the head H is relatively lowered and shifted d) and the magnetic tape is tilted (angle γ) is shown. In this case, the phases of the outputs of channels A and C advance (the output time point is advanced), and the outputs of channels B and D are delayed in phase (the output time point is delayed).

  As shown below, the shift d and the inclination angle γ can be obtained.

  When the magnetic tape 1 travels at an angle (γ) (assuming β = 0), the angle γ of the direct tilt is tan γ = V (t′C−t′D) from the phase difference between the outputs of the channels C and D. / (YD-yC).

  Further, if the phase difference between the channels C and D is ignored (in short, the shift d, which is the positional information of the head H is obtained from only the phase difference between the channels A and B), the inclination of the magnetic tape 1 is also ignored (γ = 0). Is considered).

  Next, a case where a shift d due to LTM, a change in azimuth angle due to deformation, ± β, and a tilt angle γ occur in combination on the magnetic tape having the servo pattern 2d will be described. When the servo pattern 2d is composed of an equal positive / negative azimuth angle segment, two segments having an azimuth angle of 0 degree, and another equal positive / negative azimuth angle segment, positional information of the head H in the track width direction ( The principle of detecting the shift d), the information on the width of the magnetic tape 1 (angle β), and the information on the tilt of the magnetic tape 1 (angle γ) will be described.

  6 and 7 are explanatory views of the principle of detection of information on the structure of the servo pattern 2d, the head position, magnetic tape deformation, and magnetic tape tilt.

  As shown in these figures, the channels A, B, C, D, E, and F of the head H of the magnetic tape device are on the same gap line, and the y-axis of the channels A, B, C, D, E, and F Assuming that the directional positions YA, YB, YC, YD, YE, YF and the azimuth angle α are known, consider the point in time when the head H outputs a signal in response to the magnetization reversal of the servo pattern.

  Next, a calculation formula for calculating the shift of the magnetic tape will be described.

  Equations (8-1) and (8-2) shown in FIG. 6 can be modified as follows.

  As shown in FIG. 7, the origin is shifted by X ′ in the −X direction as compared with FIG. 6 (that is, XNEW = X + X ′).

Y0: Data band pitch α: Azimuth angle (Y0tan α = 2X0)
X1: A shift amount for determining a servo pattern.

  At this time, each part of the servo pattern shown in FIG. 7 is represented by Expression (11-1), Expression (11-2), Expression (11-3), and Expression (11-4) as shown below.

  Considering the angle β (change angle when the magnetic tape spreads in the width direction), when the azimuth angle α is replaced with α-β, the following equations (11-1 ′), (11-2 ′), Expressions (11-3 ′) and (11-4 ′) are obtained.

  Considering the angle γ (the angle of inclination during running of the magnetic tape), the following equations (12-1) and (12-2) are obtained.

  In addition, the point (X (two dash), 0) moves to (X (three dash), Y (three dash)), and the expressions (12-1) and (12-2) are converted into the expressions (12- 3) and Equation (12-4). However, X (two dash) = 2X0−X1, 2X0 = Y0tanα.

式（１２−１）〜式（１２−４）を基にシフトｄを考慮すると、次に示す式（１３−１）、式（１３−２）、式（１３−３）及び式（１３−４）が得られる。

Considering the shift d based on the formulas (12-1) to (12-4), the following formulas (13-1), (13-2), (13-3), and (13- 4) is obtained.

  Here, assuming that the positions in the Y direction of the channels A, B, C, and D of the head H are YA, YB, YC, and YD, the following expressions (13-1 ′), (13-2 ′), and (13-3 ′) and Equation (13-4 ′) are obtained. From these equations, the following equations (13-5 ′) and (13-6 ′) are obtained.

  From these equations, the following equation (13-7) for obtaining the shift d is obtained.

  Here, YA and YB are known, and XA−XB is obtained from the measured value (the time difference between the channel A and B outputs). Therefore, if K1 and K2 are obtained from the equations (13-5 ′) and (13-6 ′), the shift d can be obtained using the equation (13-7).

  Thus, when the shift d is obtained from the elapsed time or the time difference of the outputs of the channels A, B, C, and D, the equation (13-7) is obtained, but the inclination angle γ is unknown. Therefore, the shift d can be obtained by obtaining the inclination angle γ from the time difference between the outputs of the channels E and F. The length X1 in the X-axis direction (part of the servo pattern format) used in this process needs to be corrected including the deformation in the longitudinal direction of the magnetic tape using the magnetic tape speed at the time of servo pattern measurement. There is. The longitudinal deformation of the magnetic tape results in a magnetic tape speed deviation.

by the way,
X (three dash) = X (two dash) cosγ
Y (three dash) = X (two dash) sinγ
X (two dash) = Y0 · tan α−X1
on the other hand,
tan γ = (XE−XF) / (YF−YE)
γ = tan ⁻¹ [(XE−XF) / (YF−YE)] (13-8)
Here, YF and YE are known, and XE-XF is obtained from the measured values. If these are substituted into the formula (13-5 ′) and the formula (13-6 ′), as shown in the following formula (14-1) and formula (14-2), all of K1 and K2 are known values. Alternatively, it is expressed by a value obtained from a measured value.

  Therefore, the shift d can be obtained by substituting the equations (14-1) and (14-2) into the equation (13-7). For example, the angle β can also be obtained using the equation (13-5 ′).

Magnetic tape speed detection The magnetic tape device basically measures the servo pattern cycle. When there is a segment with an azimuth angle of 0 degrees in the servo pattern as shown in FIGS. 6 and 9, for example, the first servo pattern in the longitudinal direction of the magnetic tape from the first transition of this segment is simply used. What is necessary is just to measure the period of the 1st transition (transition) in.

  On the other hand, when there is no segment having an azimuth angle of 0 degrees in the servo pattern as in the servo pattern 2b shown in FIG. 4, for example, the first segment and the negative segment (for example, channels A and B) having a positive azimuth angle are used. If the period between each transition is measured and the magnetic tape speed is obtained from the average, the influence of the LTM fluctuation (shift d fluctuation) can be reduced. Note that the method of measuring the period of the segments above and below the center of the data band and taking the average can also be used for segments with an azimuth angle of 0 degrees, in which case the effect of magnetic tape tilt is reduced. it can.

  As described above, according to the present embodiment, the servo pattern 2, the guard space 4, the data burst 3, the guard space 4, the servo pattern 2, and the guard space are provided on the data bands b0 to b3 provided in the width direction of the magnetic tape 1. 4, data bursts 3,... Are arranged.

  In order to record data in the data burst 3, it is assumed that the servo pattern 2 has been recorded in advance, and at the start of recording, usually a plurality of servo patterns 2 are usually used by the reproducing head H2 on the same bump as the upstream recording head H1. After reproducing (controlling the recording current during this period) and controlling the position of the head H, the recording current is supplied to the upstream recording head H1 to record the data, and after a certain period of time (just before the next servo pattern). ) Stop the recording current. The next servo pattern 2 is reproduced again by the reproducing head H2 having the same bump, the head position information is detected, and immediately after that, data burst recording is started again. Thereafter, the recording, reproduction and head position control are repeated until the recording is completed. During recording, read after-write (or read-and-write write) is performed using the bump reproducing head H2 located downstream.

  That is, when the upstream and downstream (different bumps) recording heads H1 and reproducing heads H2 are used, there is a problem that the recording data track position is shifted due to the inclination of the traveling direction of the magnetic tape 1. In the present invention, the recording head H1 and the reproducing head H2 of the bumps on the same upstream side are alternately used in a time division manner, whereby the servo pattern 2 is reproduced by the reproducing head H2 closer to the recording head H1, and the head is based on accurate servo information. The position of H can be controlled more accurately, the head H can be guided to the optimum position, and data can be recorded at the accurate position. Further, the problem of crosstalk from the recording head H1 to the reproducing head H2 can be solved during recording.

FIG. 8 is a partial plan view of a conventional magnetic tape apparatus head and a conventional magnetic tape.
That is, conventionally, as shown in FIG. 8, the two-bump type head H ′ includes head blocks HB1 ′ and HB2 ′ in which the reproducing head H2 is piggybacked on the recording head H1 (or vice versa). The two heads H ′ are aligned in the opposite direction, and the head block HB1 ′ (the first bump (upstream bump) constituting the recording head) is formed on the recording / reproducing heads H1, H2, and the head block HB2. ′ (The second bump constituting the (downstream bump)) heads H2 and H1 are arranged for reproduction / recording (or in the reverse order), and the first bump recording head H1 is the second bump. The reproducing head H2 of the first bump and the reproducing head H2 of the first bump are aligned with the recording head H1 of the second bump. A servo gap is formed on the reproduction gap.

  Thus, for example, by separating the recording gap (upstream side) and the reproducing gap (downstream side) by about 1 millimeter, crosstalk from the recording head H1 to the reproducing head H2 is reduced.

  As shown in FIG. 8, conventionally, the magnetic tape 1A is divided into a plurality (for example, 4) in the width direction, and a data band 3A and a servo band 2A are provided in the width direction of the magnetic tape 1A, respectively. At the time of recording, the reproducing head H2 that is on the same bump as the recording head H1, even though it is a servo channel S outside the data channel, cannot be used for reproducing servo signals due to crosstalk from the recording head H1. Therefore, the servo signal is detected by the servo channel of the reproducing head H2 of the adjacent bump located downstream in the running direction of the magnetic tape 1A, and the position of the recording head is controlled. If the running of the magnetic tape 1A is tilted in this state, the position of the recording head H1 will deviate from the correct position accordingly, and the track density will be restricted. In the normal method, in order to reduce the influence of the traveling inclination of the magnetic tape 1A, the distance between the gap line of the head block HB1 ′ and the gap line of the head block HB2 ′ is reduced. There are restrictions and it is difficult.

  That is, the tracking operation always tries to align the reproduction gap with the reference track center. Therefore, as shown in FIG. 9, when the direction (inclination) in which the magnetic tape runs in front of the head changes dynamically (tape meandering), the position of the recording gap is between the tangent of the inclination angle and the gap (longitudinal direction). Track deviation (track misregistration) by an amount corresponding to the distance. That is, because the position of the recording track is offset, a part of the recorded adjacent track is overwritten, and the tracking margin is reduced by narrowing the track width.

  In contrast, in the present embodiment, as shown in FIG. 3, the recording head H1 and the reproducing head H2 of the same upstream bump are alternately used in a time division manner, thereby reproducing the reproducing head H2 closer to the recording head H1. Thus, the servo pattern 2 is reproduced, the position of the head H is more accurately controlled based on accurate servo information, the head H is guided to the optimum position, and data can be recorded at the accurate position. Further, the problem of crosstalk from the recording head H1 to the reproducing head H2 can be solved during recording.

  During reproduction, the servo pattern 2 is also reproduced by the reproducing head H2 (usually the downstream bump) used for data reproduction, and the position of the head H is controlled.

  When the magnetic tape 1 having the servo pattern 2b has a shift d caused by LTM (movement in the width direction of the running magnetic tape 1), a change in azimuth angle due to deformation ± β, and a tilt angle γ in combination, FIG. As shown in FIG. 5, K1 and K2 are obtained from the known value and the measured value, and as a result, the shift d, the angle β, and the inclination angle γ can be obtained. (The positioning information (shift d) in the track width direction of the recording head H1 or the reproducing head H2 is corrected (determined) using deformation information (angle β) and / or inclination information (angle γ) of the magnetic tape 1. As a result, the data can be recorded and reproduced accurately by adjusting the position of the head H.

  When the magnetic tape 1 having the servo pattern 2e is generated in combination with the shift d by LTM and the tilt angle γ, the tilt angle γ is obtained directly from the phase difference between the outputs of the channels C and D, [Equation 2] The shift d can be obtained from the equation shown below. As a result, the data can be recorded and reproduced accurately by adjusting the position of the head H.

  When the shift d due to LTM, the azimuth angle change due to deformation occurs ± β, and the tilt angle γ in combination with the magnetic tape having the servo pattern 2d, the shift d is obtained from the equation (13-7), and the equation (13 -8 can be obtained from -8). As a result, the data can be recorded and reproduced accurately by adjusting the position of the head H.

By recording and reproducing the magnetic tape 1 having the servo pattern 2 by the linear magnetic tape device having the multi-channel head H, in addition to the position information in the width direction of the normal magnetic tape 1, the deformation of the magnetic tape 1 Positioning information corresponding to the deviation caused by the inclination of the head H can be detected, and the track density (TPI) can be dramatically increased.
In the past, the track pitch was supposed to be as narrow as possible, but an example of a magnetic tape will be shown below.
FIG. 10 is a diagram illustrating the positional relationship between the servo pattern and the data band and the relationship between the head channel position and the path according to one embodiment.

  As shown in FIG. 10, the data band pitch that is the pitch in the width direction of the data band is 640 micrometers, 16 track parallel recording / reproduction, and one data band is completed in 16 passes (8 reciprocations) (track pitch is 2.5 micrometers), LTM is ± 15 micrometers or less, and the head is set to 17 channels (channel 17 (CH17): auxiliary servo channel) in consideration of servo, but it is not limited to this. Absent.

  The frequency of inserting the servo pattern is naturally better from the standpoint of sampling, but the viewpoint of redundancy and the detection sensitivity of head position information, magnetic tape width information, and magnetic tape tilt information In addition, it is necessary to search for an optimal combination of frequency and servo pattern in consideration of the assumed LTM.

  Hereinafter, the servo pattern will be described with reference to the example shown in FIG. 7 which is the most complicated and has the shortest exclusive length in the longitudinal direction (redundancy is low), but the same applies to other patterns. .

In the servo pattern, the positive and negative azimuth angle segments each have a width of 80 micrometers, and the width of the segment having an azimuth angle of 0 degrees is 200 micrometers. Note that the normal servo pattern is composed of a plurality of magnetization reversals, but one magnetization reversal is shown here. The positions of the servo pattern and the data band in the tape width direction are offset by 18.75 micrometers (20 at the upper end of the track) in pass 1. Normally, the tape runs from BOT to EOT for odd paths and from EOT to BOT for even paths. Each channel constitutes a data subband with a total of 16 paths (8 round trips). The odd 8 passes and the even 8 passes form separate track groups, and it is avoided as much as possible that the tracks by the return pass are not adjacent to each other. In this example, the path 16 and the path 1 track of the adjacent channel, the path 15 and the path 2 track, and the path 16 and the path 1 track of the adjacent channel correspond. In addition to data, data band and path identification information may be inserted at a predetermined position of the data burst 3. In addition, when providing a guard band, it puts between these tracks (the tape running direction is reverse). (In general, a guard band is a data band and a data band, or an area that separates tracks from each other. The data band is not necessarily required for formatting.) The head channel in each path and the channel shown in FIG. Of A: CH10, B: CH8, C: CH17, D: CH1, E: CH14, F: CH4. CH1 to CH1 are data channels, and CH17 is an auxiliary channel for servo. By taking the offset, the value of d in equation (13-7) is N as the pass number:
d = dN + LTM
dN = −18.75 + {2.5 × (N−1) / 2}
N = 1, 3, 5,..., 15 (BOT → EOT)
dN = {2.5 × (N−1) / 2}
N = 2, 4, 6, ..., 16 (EOT → BOT)
It becomes.

YA and YB are track centers:
YA = -40
YB = + 40
(Unit: micrometer) (based on CH9 track center).

Similarly,
YC = −320
YD = + 320
YE = -200
YF = + 200
(Unit: micrometer).

  By taking the offset, the head does not deviate from the respective segment for any expected path of ± 15 micrometer LTM. Further, the servo pattern direction (relative to the magnetic tape running direction) is reversed depending on the combination of odd and even numbers of N and the data band number.

  Now, in order to determine the azimuth angle and the interval and the number of magnetization reversals when the data subband width (head channel spacing) is determined, the following is considered. LTM detection sensitivity, for example, how many micrometers of LTM you want to convert to a change in longitudinal position (detected as time). Even in the case of the maximum expected LTM, because of the azimuth angle, isn't it erroneously detected by the adjacent magnetization reversal of the same polarity? Are the redundancy and sampling period determined by the minimum number of magnetization reversals and the length of the data burst necessary and sufficient (converted to frequency, about 10 times the required servo bandwidth)? In order to increase the detection sensitivity of LTM, increasing the azimuth angle and other conditions are contradictory, so a compromise point will be searched.

  As an example of this, the positive and negative azimuth angles are about ± 14 degrees (tan α = 0.25). As a result, X1 in FIG. 7 is 70 micrometers. The interval between adjacent servo patterns is 1 mm. Therefore, if the magnetic tape speed is 10 meters / second, the frequency at which LTM is sampled is 10 KHz. Also, 1 micrometer LTM is converted to a length of 0.5 micrometers in the longitudinal direction thanks to positive and negative azimuth angles. This corresponds to a time of 50 nanoseconds (5E-8 seconds) at a magnetic tape speed of 10 meters / second. If the time is measured with a 1 GHz clock counter, an LTM of about 0.1 micrometers can be detected (a difference of about 5 counts). The resolution is sufficient for a track pitch of 2.5 micrometers. Incidentally, at this time, when the inclination of the magnetic tape and the detection sensitivity of the deformation of the magnetic tape are set to a difference of 5 counts (corresponding to a change / deformation of about 5 nanometers in the longitudinal direction), the inclination (angle γ) is about 7E-3. Degree and deformation (angle β) is about 8.5E-3 degrees. It is also known that with the help of an analog circuit, time can be measured with sub-nanosecond resolution while using a lower frequency clock.

  The length of the data burst 3 at this time is about 800 μm in total, assuming that the interval of the servo pattern (transition) is 4 transitions at 10 μm and the guard space 4 before and after the servo pattern is about 80 μm. It becomes the length. That is, the utilization efficiency in the longitudinal direction of the magnetic tape 1 is about 80%.

  The servo pattern of 4 transitions is obtained by making the second transition closer to the first transition, or moving the third transition away from the first transition, or by position (phase) modulation (transition having the same polarity, first transition). And the third or second and fourth distances are modulated so as not to be closer than 20 micrometers), a unique pattern for frame synchronization and 1-bit data can be expressed (multi-valued) If modulated, it is possible to express multi-bit data). That is, when recording the servo pattern 2 with the recording head 308 (servo pattern full-width recording head) having a recording gap 309 (see FIG. 17) having the same shape as the boundary shape of the magnetization transition, the magnetic tape 1 full width is recorded. Different servo patterns can be formed by modulating the timing of the change in the recording current to express binary data and a unique synchronization signal. Furthermore, a data frame composed of a unique synchronization signal and a plurality of data bits can be formed using a plurality of servo patterns. When the servo pattern 2c shown in FIG. 2C is formed, a plurality of servo patterns may be formed by modulating the timing of change of the recording current to obtain binary data and unique synchronization signals.

An example of the tracking servo configuration of the magnetic tape device is shown based on the above.
FIG. 11 is a block diagram of the tracking servo mechanism of the magnetic tape device.
Known methods can be used for the signal processing system, reel motor control system, and servo pattern data demodulation system of the magnetic tape device.

  The tracking servo mechanism 100 includes a head stack 101, an AMP / SEL (preamplifier / selector) 102, a peak detection / time measurement (distance conversion) device 103, a data burst gate 104, a flywheel 105, a tracking (LTM) detector 106, D / A (digital / analog conversion) device 107, fine movement actuator 108, and coarse movement actuator 109 are provided.

  The SEL of the AMP / SEL (preamplifier / selector) 102 selects the output from the corresponding bump according to R / W (read / write).

  The peak detection / time measurement (distance conversion) unit 103 determines the channel corresponding to the channels A, B, C, D, E, and F according to the data band select LSB (tape travel direction) and the LSB information of the pass number N. Peak detection and time measurement are performed, and speed information is used to convert to longitudinal distance.

  The data burst gate 104 receives the output of the flywheel 105 and masks the servo pattern on the time axis for each data channel (CH1, CH2,..., CH16). Although not shown, in order to protect the servo pattern on the recording side, a functional block that receives the output of the flywheel 105 and gates the recording current is also inserted.

  The flywheel 105 is a known PLL (phase synchronization system) having different time constants in the capture mode and the lock mode.

  The tracking (LTM) detector 106 receives the output of the peak detection / time measurement (distance conversion) device 103, calculates the shift d, and obtains a tracking error (LTM) using the pass number information. The servo loop works to bring this value closer to zero. The other output of the peak detection / time measurement (distance conversion) device 103 is used to control the reel motor by detecting the magnetic tape speed (converting the pulse train period to speed information). Then do not enter.

  The fine motion actuator 108 and the coarse motion actuator 109 are, for example, a pulse motor and a screw that drive the stage based on information on the stage and pass number that is driven by the moving coil and the data band designation information that drives the head H held by a spring. is there. In addition, these can also be comprised with a linear motor with a long stroke. The fine actuator 108 and the coarse actuator 109 are known techniques.

  Next, an example of the configuration of the peak detection / time measurement (distance conversion) device 103 and tracking (LTM) detector 106 of the present invention is shown (other blocks can be realized by a known technique).

FIG. 12 is a block diagram showing details of the peak detection / time measurement (distance conversion) device 103 of the tracking servo mechanism. Here, an example in which a built-in clock is used for time measurement is shown.
The peak detection / time measurement (distance conversion) device 103 includes a peak detector 131, a time sampler 132, a distance detector 133, a built-in clock 134, and a pulse shaper 135.

  The peak detector 131 includes a low-pass filter, a narrow peak detector (detects positive and negative peaks separately), and a selector, and selects and outputs either positive or negative detection peaks. The role of the low-pass filter is to attenuate data bursts and noise to prevent erroneous detection of servo patterns.

  The time sampler 132 obtains the time by sampling the output of the built-in clock 134 with the output of the peak detector 131.

  The distance detector 133 takes the difference between the outputs of the time sampler 132, multiplies it by the magnetic tape speed, converts it to a distance, and inverts the sign in accordance with the pass number information (ie, tape running direction information) and data band information. .

  The built-in clock 134 is a counter and only needs to have a cycle longer than twice the time between the same-polarity transitions of the servo pattern (a positive / negative time between transitions is necessary due to the magnitude relationship between the two time inputs). In this example, a 13-bit counter with a clock of 1 GHz is appropriate. This is because the output period of this counter is just over 8 microseconds, whereas the 20-micrometer interval between the same polarity transitions corresponds to 2 microseconds at a magnetic tape speed of 10 meters / second. .

  An example of the pulse shaper 135 includes a retrigger mono-multivibrator whose pulse width T is longer than the transition interval (in this example, the interval is 2 microseconds, that is, 2 <T << 100).

  FIG. 13 is a block diagram showing details of the tracking (LTM) detector 106 of the tracking servo mechanism.

  The tracking (LTM) detector 106 includes a cos γ and sin γ calculator 61, a K 1 calculator 62, a K 2 calculator 62 ′, a d calculator 63, an LTM calculator 64, and a dN calculator 65.

  The cos γ, sin γ calculator 61 first obtains γ from ± (XE−XF) from the distance detector 133 and the known YF, YE (since the value of γ is small, it may be a linear approximation), and then calculates cos γ, sin γ. Find this (appropriate approximation to the second term by expanding the series from the relationship with other constants).

  The K1 calculator 62 and the K2 calculator 62 ′ receive ± (XA-XD) and ± (XB-XC) from the distance detector 133 and cosγ and sinγ from the cosγ and sinγ calculator 61, respectively. K1 and K2 are calculated (four arithmetic operations) using Y0 (data band pitch), tan α (= 0.25), X1 (= 70), YA, YD, YB, and YC.

  The d computing unit 63 receives ± (XA−XB) from the distance detector 133 and K1 and K2 from the K1 computing unit 62 and the K2 computing unit 62 ′, together with the known YA and YB, the equation (13− The shift d is calculated (four arithmetic operations) according to 7).

  The LTM calculator 64 calculates the LTM by taking the difference between the output d of the d calculator 63 and the output dN of the dN calculator 65.

  The dN calculator 65 converts the pass number N into dN (simple table lookup). In this example, the LSB (least significant bit) of the pass number N (N = 1, 2,..., 16) represents the tape running direction.

FIG. 14 is a block diagram illustrating details of another tracking (LTM) detector 106 ′.
The tracking (LTM) detector 106 ′ includes a γ calculator 61 ′ and a d calculator 63 ′ in addition to the LTM calculator 64 and the dN calculator 65.

  The γ calculator 61 ′ calculates an approximation (linear approximation) of γ.

  An example of calculation for obtaining an approximate solution using the γ calculator 61 ′ and the d calculator 63 ′ will be described. The d calculator calculates the expression (22-1) and obtains d.

  If the magnetic tape speed is changed, for example, 5 meters / second, the frequency is halved and the time is doubled. At this time, it is desirable that the cutoff frequency of the low-pass filter is also halved. On the other hand, in the time measurement, the clock frequency is halved and the count number is maintained. Alternatively, it is conceivable to maintain the clock frequency and double the number of counts. Needless to say, even when other speeds are used, the cut-off frequency of the low-pass filter and the time measurement method may be changed in proportion to the speed.

A servo pattern recording method will be described with reference to the example shown in FIG.
In converting the length on the magnetic tape into the time axis of the signal generator, the tape speed is 10 meters / second. For other speeds, the time value may be inversely proportional to the speed (5 meters / second is all doubled).

  FIG. 15A shows a magnetization pattern on the magnetic tape, and FIG. 15B shows a current waveform for recording the magnetization pattern. FIG. 15C shows an example in which a servo pattern composed of 4 transitions is modulated to represent a 1-bit address or data, or a unique sync (synchronization) pattern 1 or 2.

  FIGS. 16A and 16B are images on a magnetic tape. As an example, both extreme examples of the frame configuration when a 20-bit address and 128-bit management data (128 bits may be data + error control bits) are inserted. Show.

  In FIG. 16A, one frame is composed of 128 bits of data for one address, whereas in FIG. 16B, one frame is composed of 1 bit of data for one address, and one frame is composed of 128 subframes. .

  In the former, the length of one frame is as short as 0.15 meters, but the address is also 0.15 meters.

On the other hand, in the latter, the length of one frame is a little over 2.8 meters, but the address unit is the shortest, 22 millimeters.
The latter is preferred because of the nature of the address and management data.
In any case, sync pattern 0 is used as frame synchronization, and sync pattern 1 is used as a sub-frame separator.

In the following, the case of FIG.
The 20-bit address satisfies the conditions shown in the paragraph 0116 described above and generation of a modulo address sufficiently longer than the longest tape that can be handled by the servo pattern recording apparatus.

That is, when the longest tape length that can be handled by the servo pattern recording apparatus is 5000 meters, for example, when the unit length of the address is 22 millimeters,
(5000 / 0.022) = about 227273 <262144 = 2 to the 18th power Therefore, 18 bits are sufficient.

If the unit length of the address is 0.15 meters, 16 bits are sufficient.
FIG. 17 is a configuration example of the servo pattern recording apparatus 300 having the frame configuration shown in FIG. 16B.
The 2 MHz clock Ck (cycle 0.5 microsecond) is divided by 1/200 by a 1/200 divider 301 to form a servo pattern cycle (100 microseconds), and then 1/22 divided. The frequency is divided by 1/22 by the unit 302 to form a subframe period (2.2 milliseconds), and the 20-bit address generator 303 is incremented.

  Further, it is divided by 1/128 by a 1/128 frequency divider 304 to form a frame period (281.6 milliseconds).

  The address generator 303 is reset every time the long magnetic tape 1 is loaded into the servo pattern recording apparatus 300 via the controller 305.

  This guarantees that the address in the long tape 1 monotonically increases (thus, the address of the tape that is partially cut out and wound into the cartridge also monotonously increases).

  The pattern generator 306 receives the clock, servo pattern period, sub-frame period, frame period, 20-bit address data, and in addition to these, 128-bit management data via the controller 305, and receives the servo pattern of FIG. 15B. Generates a modulated signal as shown in FIG. 15C.

  The output of the pattern generator 306 is supplied to the recording head 308 via the amplifier 307. As an embodiment, there is a method in which one servo pattern of 4 transitions represents 1-bit data or a unique sync pattern, and a subframe is composed of an address and 1-bit data, and a frame is composed of a plurality of subframes. Although described, other cases can be realized by the same consideration, for example, when the number of transitions is large, in the case of multi-level modulation, in the case where a subframe is configured with an address and a plurality of data bits.

  The recording head 308 is a servo pattern full width recording head that includes a ferrite ring and can record the servo pattern 2 over the entire width of the magnetic tape 1. The recording head 308 includes a recording gap 309 having the same shape as the boundary shape of the magnetization transition of the servo pattern 2.

  When recording the entire width of the magnetic tape 1 with the recording head 308, the controller 305 controls the number of changes in the recording current to all odd numbers (every servo pattern 2) or all even times.

  The servo pattern recording apparatus 200 may include a full width erasing head (not shown). The full width erasing head is used for erasing a part 2c ′ of the servo pattern 2c shown in FIG. 2C to form a data area.

  When the servo pattern 2 is recorded on the entire width of the magnetic tape 1 by the recording head 308, binary data or a unique synchronizing signal can be expressed by modulating the timing of change of the recording current.

  The servo current 2 is first recorded on the magnetic tape 1 by the recording head 308, and then a part of the recorded servo pattern is erased so that a data recording portion is formed by the subsequent full width erasing head. By controlling the operation timing of the modulation and subsequent full width erasing head, binary data can be expressed in the servo pattern 2 or a unique synchronizing signal can be expressed.

  The servo pattern 2 can correspond to 1-bit data, or can correspond to 1-bit data or a unique synchronization signal.

  In the above description, no guard band is provided at the boundary of the data band and at the center and boundary of the data subband. However, the tracks on both sides sandwiching these lines are not recorded / reproduced by running the magnetic tape in the reverse direction. Needless to say, the present invention is effective when a guard band is installed or when a combination of parameters (data band pitch, track pitch, servo pattern, etc.) other than the example shown here is used.

  One data band b 0 may be provided in the width direction of the magnetic tape 1. In addition, the guard band between the data band b0 and the data band b1 may have a width of 0 (zero).

  For example, when the servo pattern 2a shown in FIG. 2 is recorded with the recording head 308 (servo pattern full width recording head) having the recording gap 307 shown in FIG. 17 having the same shape as the boundary shape of the magnetization transition, the magnetic tape 1 full width is recorded. The number of changes in the recording current is all odd or all even.

  In the above embodiment, information on deviations from the reference position of the individual positions of the recording and / or reproducing gap of the recording head H1 and the reproducing head H2 is stored in the magnetic tape device, and the information is used to record the recording head. The position information of the H1 and the reproducing head H2, the deformation information of the magnetic tape 1, the tilt information of the magnetic tape 1, the magnetic tape speed information, and / or the phase information of the magnetic tape 1 are corrected.

  The distance detector 133 takes the difference between the outputs of the time sampler 132, but the elapsed time or the measured time difference between the outputs may be detected as a phase difference by a burst phase comparator.

  As shown in FIGS. 2 (A) and 2 (B) in servo pattern 2, when there is no (recording) segment with an azimuth angle of 0 degrees, the servo of the output of the reproduction channel corresponding to the segment with a positive azimuth angle It is also possible to measure the period of the pattern and the period of the servo pattern of the output of the reproduction channel corresponding to the negative segment, and perform the calculation in consideration of the absolute value of each azimuth angle to obtain speed information.

  Further, each of the positive and negative azimuth angle segments of the servo pattern 2 is sequentially reproduced by the upstream reproducing head H2 and the downstream reproducing head H2, and the difference between the elapsed time or the measured time and the gap between the upstream and downstream reproducing heads H2, respectively. After obtaining the first speed information and the second speed information from the distance, the information about the tape tilt angle and the azimuth angle may be taken into consideration to calculate the speed information.

The magnetic tape device may be provided with a control mechanism that controls the tilt angle of the head H in accordance with, for example, tilt information (angle γ) of the magnetic tape 1. In this way, the read head can be correctly positioned on the track during read after write (read whistle write). On the contrary, the recording head can be positioned by using the reproducing head of the downstream bump during recording.
When the phase of the magnetic tape 1 is locked by a frequency multiplier (not shown) or the like, and there is a segment with an azimuth angle of 0 degrees in the servo pattern 2, the period (frequency) of the output servo pattern of the channel for reproducing the segment is The frequency is divided by a frequency divider (not shown) as necessary, and the phase is compared with the reference signal.

  When the magnetic tape 1 is phase-locked and there is no segment with an azimuth angle of 0 degrees in the servo pattern 2, the period (frequency) of the output servo pattern of the reproduction channel corresponding to the segment with a positive azimuth angle is set to a predetermined value. Divide as many times as necessary by the division ratio of the first reference signal and compare the phase with the first reference signal, and the period (frequency) of the output servo pattern of the playback channel corresponding to the negative segment is divided by the same division ratio. The phase may be compared with the second reference signal and the outputs of the respective phase comparators may be phase-locked by calculating in consideration of the absolute value of the azimuth angle.

  A tape mark may be formed using one or a plurality of data bursts 3. The end of data can be represented by a tape mark (file mark).

b0 to b3 Data band s1, s2 Segment G Boundary line H Head H1 Recording head H2 Playback head CH17 Auxiliary channel for servo α Azimuth angle β Angle γ (Inclination) angle 1 Magnetic tape 2 Servo pattern 3 Data burst (data)
4 Guard space 300 Servo pattern recording device 305 Controller 308 Recording head 309 Recording gap

Claims (17)

A recording head for recording data via a guard space between the servo patterns on a magnetic tape having servo patterns arranged at equal intervals in the longitudinal direction of the data band of the magnetic tape;
The data recorded on the magnetic tape and the data band of the magnetic tape are composed of at least two segments in the width direction of the data band, and adjacent segments of the segments are formed with different azimuth angles. And a reproducing head for reproducing the servo pattern,
A magnetic tape device comprising detection means for detecting positioning information of the recording head or the reproducing head, deformation information of the magnetic tape, and / or tilt information of the magnetic tape based on an output from the reproducing head. The magnetic tape device according to claim 1,
For reproduction of the servo pattern, at least two channels of data channels of the reproduction head are used. From the correlation between reproduction servo signals from each channel, magnetic tape speed information, and reproduction head channel information, A magnetic tape device that detects positioning information of the recording head or the reproducing head, deformation information of the magnetic tape, and / or tilt information of the magnetic tape. The magnetic tape device according to claim 1,
For reproducing the servo pattern, at least two channels are used from among the data channel and servo auxiliary channel of the reproducing head, the correlation between reproduced servo signals from each channel, magnetic tape speed information, and reproducing head The magnetic tape apparatus detects the recording head or reproducing head positioning information, the magnetic tape deformation information, and / or the magnetic tape tilt information from the channel information. The magnetic tape device according to claim 1,
A magnetic tape device that reproduces the servo pattern using a reproducing head piggybacked on the upstream recording head during the magnetic data recording. The magnetic tape device according to claim 1,
A magnetic tape device for reproducing the servo pattern by using the reproducing head downstream at the time of reproducing the data. The magnetic tape device according to claim 1,
A magnetic tape device that inserts the data band and / or path identification information at a predetermined position in an area for each path, which is a component of a data area sandwiched between the servo patterns. The magnetic tape device according to claim 1,
A magnetic tape device that treats an integral multiple as a physical block for each pass in units of a data area sandwiched between the servo patterns, an adjacent preceding or succeeding servo pattern, and an accompanying guard space. The magnetic tape device according to claim 1,
For each pass, a magnetic tape that forms a tape mark using one or a plurality of data areas sandwiched between the servo patterns, adjacent preceding or following servo patterns, and accompanying guard spaces. apparatus. A recording head for recording servo patterns at equal intervals in the longitudinal direction of the magnetic tape;
Control means for controlling the current supplied to the recording head when the servo pattern is recorded by the recording head;
A servo pattern recording apparatus for recording a servo pattern, which is composed of at least two segments on the magnetic tape and in which adjacent segments are formed with different azimuth angles. The servo pattern recording apparatus according to claim 9, wherein
The recording head has a recording gap having the same shape as the boundary of the magnetization transition of the servo pattern to be recorded on the magnetic tape, and records the servo pattern over the entire width of the magnetic tape;
A servo pattern recording apparatus comprising: control means for controlling the number of changes in recording current per servo pattern to all odd times or all even times when recording the full width of the magnetic tape with the recording head. The servo pattern recording apparatus according to claim 10,
A servo pattern recording apparatus that expresses binary data or a unique synchronization signal by modulating a change timing of a recording current when recording the full width of the magnetic tape with the recording head. The servo pattern recording apparatus according to claim 9, wherein
The recording head has a recording gap having the same shape as the boundary of the magnetization transition of the servo pattern to be recorded on the magnetic tape, and records the servo pattern over the entire width of the magnetic tape;
Servo pattern recording apparatus for forming the servo pattern by first recording on the magnetic tape by the recording head and then erasing a part of the servo pattern by a subsequent full width erasing head so as to form a data recording area . The servo pattern recording apparatus according to claim 12,
When the servo pattern is first recorded on the tape by the recording head and then a part of the recorded servo pattern is erased so as to form a data recording area by the subsequent full width erasing head, the recording current is modulated. A servo pattern recording apparatus that controls the operation timing of the subsequent full-width erasing head to express binary data in a servo pattern or a unique synchronization signal. The magnetic tape device according to claim 2,
If there is no segment with an azimuth angle of 0 degrees in the servo pattern, the period of the servo pattern output from the playback channel corresponding to the positive segment of the azimuth angle and the servo pattern output from the playback channel corresponding to the negative segment A magnetic tape device that measures the period and uses the absolute value of each azimuth angle to calculate the speed information. The magnetic tape device according to claim 3,
If there is no segment with an azimuth angle of 0 degrees in the servo pattern, the period of the servo pattern output from the playback channel corresponding to the positive segment of the azimuth angle and the servo pattern output from the playback channel corresponding to the negative segment A magnetic tape device that measures the period and uses the absolute value of each azimuth angle to calculate the speed information. The magnetic tape device according to claim 2,
Information on the deviation of the recording and / or reproducing gap from the reference position of the recording head and the reproducing head from the reference position is stored in the magnetic tape device, and the recording head and the reproducing are used using the information. A magnetic tape device that corrects head position information, magnetic tape deformation information, magnetic tape tilt information, magnetic tape speed information, and / or magnetic tape phase information. The magnetic tape device according to claim 3,
Information on the deviation of the recording and / or reproducing gap from the reference position of the recording head and the reproducing head from the reference position is stored in the magnetic tape device, and the recording head and the reproducing are used using the information. A magnetic tape device that corrects head position information, magnetic tape deformation information, magnetic tape tilt information, magnetic tape speed information, and / or magnetic tape phase information.

Images