JP2007095140A - Linear tape, drive device of linear tape and servo pattern write device of linear tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear tape capable of minimizing measurement errors due to speed irregularities and absolute speed deviations and improving tracking accuracy. <P>SOLUTION: On both sides in the tape longitudinal direction of A-D bursts constituting an LTO servo pattern respectively, auxiliary pulses 10 parallel with a line orthogonal to a tape edge and having a length roughly equal to a spacing along the line orthogonal to the tape edge between both ends in the tape width direction of the respective bursts A-D are formed at prescribed spacings in the tape longitudinal direction from the respective bursts A-D. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a linear tape in which a servo band having a plurality of servo tracks along the longitudinal direction of the magnetic tape and a data band having a plurality of recording tracks along the longitudinal direction of the magnetic tape are alternately formed in the tape width direction. The present invention also relates to a linear tape drive device and a linear tape servo pattern writing device.

  In linear tape, there is a tracking servo system in which, for example, a burst signal having a predetermined inclination angle is arranged as a servo pattern, a servo tracking reproducing head reproduces the burst signal of the servo pattern, and performs tracking control based on this reproduction output. It has been adopted.

  For example, the linear tape open (hereinafter referred to as LTO) format servo track pattern has the merit that it can be handled with one servo pattern even if the recording / playback track width of the data area of each generation is selected arbitrarily, In the generation with a large track width, the track position error is not a problem, but the track width error is not a problem in the generation with a large track width due to the change corresponding to the value obtained by arctangent of the inclination angle of the tape longitudinal direction (time axis direction). When it gets smaller, tracking errors cannot be ignored.

The configuration of an LTO servo frame pattern (Servo Frames Pattern; hereinafter referred to as a servo pattern) is described in, for example, Patent Document 1 below.
US patent US6762900B2

  Fig. 4 shows the LTO servo pattern. The center of this servo pattern is defined as follows. A cluster of each stripe (first pulse signal) is referred to as A, B, C, D burst in order from the left.

  The A burst has a width of 2.1μm ± 0.4 and has 5 pulses formed at a predetermined interval inclined by 6 ° ± 5 'with respect to the tape width direction perpendicular, and the B burst is arranged adjacent to the A burst. And five pulses formed with the same arrangement and arrangement interval as the A burst and inclined in the opposite direction to the A burst.

 The C burst is placed adjacent to the B burst and has four pulses formed with the same width, placement interval, and slope as the A burst. The D burst is placed adjacent to the C burst and the same width as the C burst. And four pulses formed at an arrangement interval and inclined in the direction opposite to the C burst.

 The group from these A bursts to D bursts is taken as one servo frame, and 36 servo frames are taken consecutively, and the distance from the leading edge of the A burst to the leading edge of the C burst is measured and averaged. The height at which the distance from the leading edge of the burst to the leading edge of the B burst is 50 μm is the servo pattern center.

  The length of this 36 servo frame is 200 μm * 36 = 7200 μm. Since the tape speed is 5.5 m / s, this means that the position of the center line is different every 5500 / 7.2 = 764 Hz. Since the servo bandwidth of the tracking actuator is much lower than this, it must be defined by an average average.

  Also, if the speed is offset from the center value, the center value is also offset, for example, if the speed deviation is 0.1%, the distance 50 μm from the leading edge of the A burst to the leading edge of the B burst is shifted by 50 nm, and 6 ° in the tracking direction Is equivalent to 10 times the arc tangent of, and corresponds to a height deviation of 500 nm.

 5A shows the peak jitter in the case of encoding “1”, and FIG. 5B shows the peak jitter in the case of encoding “0”.

 FIGS. 6 (a) and 6 (b) show measured values from the leading edge of the A burst to the leading edge of the C burst (S1 dimension in FIG. 5 (a)). The figure shows an amplitude of 0.04 μsec. Reach 5500mm / s * 0.04 μs = 220 nm. Naturally, it becomes 10 times 2200 nm in the tracking height direction.

  FIG. 6 (a) shows a first variation example, and FIG. 6 (b) shows a second variation example. The method of variation in the time axis direction is different as can be easily understood by comparing the two. In Fig. 6 (b), a fluctuation of about 50 msec., Which seems to be rotation unevenness, and jitter at a frequency much higher than this are superimposed. The fluctuation of about 50 msec. Is considered to be due to winding irregularity, but it is not always wound up again and wound in the same state. Therefore, there is a problem in reproducibility even when the average is corrected. It can be easily imagined that if the change with time is added, it will become more than this.

 On the other hand, FIG. 6 (a) is further complicated by the addition of vibration components of different frequencies. It can be seen that the fluctuation every 764 Hz = 1.3 msec. Is a very short time fluctuation. Therefore, even if the A-C burst distance is averaged over 7.2 mm (length of 36 servo frames), the average speed cannot be expressed.

For example, an AC burst distance with an average of 7.2 mm is AC ₇₂ . Then determine the AB ₇₂ to be _{AC 72/100 = AB 72/} 50 (AB burst length at 7.2mm average), a method of its position as the track center can be considered.

The elements included in the variations included in AB ₇₂ are listed below.

Consider the fluctuation factors of the S1 ( AC ₇₂ ) dimension in Fig. 5. The following factors can be considered.
(1) Speed fluctuation with servo writer
(2) Drive speed fluctuation
(3) Speed fluctuation due to Lateral Tape Motion (LTM).

Of these, the speed fluctuation due to LTM (3) can be ignored if considered as follows. The fluctuation frequency of the pitch of 100m at 5.5m / s is 5500 * 10 * e3 = 55KHz, and the LTM is at most several KHz, so the vibration at 55KHz can be ignored. Therefore, the above (1) and (2) should be considered for S1 ( AC ₇₂ ).
(2) Speed fluctuations in the drive include (2-1) reel winding diameter unevenness and (2-2) speed unevenness.
(2-1) Uneven reel winding diameter Since the reel rotation cycle can be predicted, it can be corrected. However, fluctuations beyond the rotation cycle are difficult to judge because of the drive fluctuation factors.
(2-2) Speed unevenness Average speed can be calculated, but further analysis is difficult. Also, since the drive does not have a capstan shaft like VTR (Video Tape Recorder), the tape speed accuracy is lower than VTR.
(1) Speed fluctuation with servo writer If the drive can be reproduced at an accurate speed, the speed fluctuation of the servo writer can be measured, but it is more difficult than (2), so it is difficult to grasp the speed fluctuation of the servo writer. .

  The distance between the stripes (pulses) of the A and C bursts and the stripes (pulses) corresponding to the B and D bursts is formed on the head surface on the servo writer, and is less susceptible to time axis fluctuations during magnetization. Therefore, if the difference in the distance fluctuation between the AB bursts is calculated from the distance fluctuation between the AC bursts, the speed fluctuation in the servo writer is likely to be found, but the distance fluctuation between AB includes the speed fluctuation due to the LTM. So it cannot be separated.

The above (1) and (2) may be considered for the AC burst distance S1 ( AC ₇₂ ) at an average of 7.2 mm, but the AB burst distance AB ₇₂ has a speed fluctuation due to the LTM (Lateral Tape Motion) of (3) above. Come in. Forcibly, it forced the target value at that time tracking center seeking AB ₇₂ as the _{AC 72/100 = AB 72/} 50 in consideration of the variation due to LTM. As for the reproducibility of LTM, it will fit in submicron as long as it runs on the same drive. However, when the drive changes, the running state of the tape changes and is not compatible. In addition, since the tape state changes with time, reproducibility cannot be guaranteed even with the same drive.

  As described above, the LTO servo pattern method has a problem in terms of accuracy in the absolute position detection method that is the basis of tracking.

 SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a linear tape, a linear tape drive device, and a linear tape servo pattern that improve tracking accuracy by minimizing measurement errors due to speed unevenness and absolute speed deviation. It is to provide a writing device.

  In order to solve the above problems, the linear tape of the present invention includes a servo band having a plurality of servo tracks along the longitudinal direction of the magnetic tape and a data band having a plurality of recording tracks along the longitudinal direction of the magnetic tape. Linear tapes alternately formed in the width direction, each formed on the servo band, having a predetermined width in the longitudinal direction of the magnetic tape, inclined at a predetermined angle with respect to a line perpendicular to the tape edge, and the tape Bursts having a plurality of first pulse signals each formed at predetermined intervals in the longitudinal direction are formed at predetermined intervals in the tape longitudinal direction, and are parallel to a line orthogonal to the tape edge; and The second pulse signal having a length substantially equal to the interval along the line perpendicular to the tape edge between both ends of the first pulse signal in the tape width direction is In the tape longitudinal direction on both sides of bets, it is characterized by having a servo pattern formed at predetermined intervals from each burst.

 The second pulse signal is divided into two in the tape width direction on a virtual center line of a servo pattern parallel to the tape edge, and one of the divided signals is the first pulse with respect to the other signal. It is characterized by comprising a set of pulse signals formed by shifting in the longitudinal direction of the tape at the same interval as the signal width.

 The interval between the first pulse signal of the burst and the second pulse signal adjacent thereto is the interval between two adjacent second pulse signals on the virtual center line of the servo pattern parallel to the tape edge. When the average of 1 m is 50 μm ± 0.1 and the average of 7.2 mm is 50 μm ± 0.15, it is 15 μm.

 The linear tape drive apparatus according to the present invention is a drive apparatus for reproducing the linear tape, wherein the servo pattern is reproduced along a servo track by a servo signal reproducing head, and the second pulse signal is divided. The tracking servo control is performed based on the difference between the reproduced signal of one of the signals and the reproduced signal of the other signal.

 The drive device reproduces the servo pattern along a servo track by a servo signal reproducing head, and the first pulse signal of the burst adjacent to the second pulse signal from the reproduction time of the second pulse signal. Tracking servo control is performed based on the ratio between the time Ta until the reproduction time and the time Tb from the reproduction time of the first pulse signal to the reproduction time of the second pulse signal to be reproduced next. Yes.

 Further, the linear tape servo pattern writing device of the present invention is a device for writing the linear tape servo pattern, wherein the burst tapes are arranged at predetermined intervals along the traveling direction of the magnetic tape. A first pulse generating head for generating one pulse signal, a second pulse generating head for generating the second pulse signal, and between the first pulse generating head and the second pulse generating head. And a second pulse reproducing head for reproducing the second pulse signal.

 More specifically, by adding vertical auxiliary pulses to the LTO format, timing-based servo pattern time axis direction fluctuation information is detected by an existing servo readhead, and time axis direction fluctuation is corrected relatively easily. The accuracy of the position information in the media width direction has been improved, and as a result, the tracking density can be improved.

That is,
(1) By adding an auxiliary pulse as the second pulse signal to the LTO servo pattern (burst with the first pulse signal), measurement based on speed unevenness due to tape jitter or winding diameter variation, or absolute speed deviation The error can be minimized and the tracking accuracy is remarkably improved.

 The auxiliary pulse can be realized by adding an auxiliary pulse recording / reproducing head to the current servo pattern forming apparatus, and has the merit that it can be realized without significant apparatus change.

 Also, migration can be improved without changing the basic dimensions of the current LTO servo pattern. Furthermore, the auxiliary pulse added LTO servo pattern can be reproduced without changing the servo track read head of the drive. (2) The auxiliary pulse has an azimuth perpendicular to a virtual line connecting the lower edge of the medium as a reference line (center line). The width of the auxiliary pulse in the vertical direction matches each servo pattern. The auxiliary pulse is divided into two at the center between the top and bottom of the LTO servo pattern, and the divided upper and lower sides are shifted by 2.1 μm in the medium longitudinal direction.

 The horizontal position of the center in the auxiliary pulse of the pair is set to 15 μm on the virtual center line of the LTO servo pattern to the first pulse leading edge of each A, B, C, D burst. This prevents both sides from interfering over the entire LTO servo pattern width.

The horizontal interval between the centers of the auxiliary pulses of the pair is 50 μm ± 0.1 (1 m average) and 50 μm ± 0.15 (7.2 mm average).
(3) The line connecting the opposite edges of the pair of auxiliary pulses is a virtual line connecting the lower edge of the medium described in (2) above and parallel to the reference line, and the virtual line of the LTO servo pattern described in (2) above. Record to match the centerline.

 The pair of auxiliary pulses described in (2) above is reproduced across the servo read head, and the point where the output of both auxiliary pulses is equal is the center line of the LTO servo pattern, so that 36 frames like the current LTO drive It is possible to determine a true center line that is accurate and not virtual, without going through the process of averaging over a range.

 The auxiliary pulse can always be reproduced at the same time (in the same phase) regardless of the position of the actuator. In addition to the AB pulse width and CD pulse width of the conventional tracking position information, time difference information from the auxiliary pulse to each pulse Has the advantage of increased accuracy.

Because speed correction is possible even if the accuracy of the speed irregularity of the current servo pattern forming device is reduced, it is possible to reduce the maintenance cost of the current servo pattern forming device and the specifications of new production, and it is possible to reduce the new production cost .
(4) In the upper (lower) half of the servo track, the time Ta from the edge after the upper pulse signal of the above auxiliary pulse (before the lower pulse signal) to the beginning of the A burst is used as the numerator, and the next auxiliary pulse from the beginning of the A burst. The tracking position information is the ratio when the time Tb until the edge after the upper pulse signal (before the lower pulse signal) is used as the denominator.

 According to this tracking method, even if there is a tape speed deviation or tape jitter, it has a proportional effect on the denominator and numerator, so the ratio value can be ignored and the absolute position information can be obtained. .

(1) According to the first to sixth aspects of the present invention, when an existing linear tape open servo pattern is used as a burst having the first pulse signal, for example, the second pulse signal is added thereto. By doing so, speed unevenness due to tape jitter and winding diameter variation and measurement error due to absolute speed deviation can be minimized, and tracking accuracy is remarkably improved.

In particular, the second pulse signal can always be reproduced at the same time (same phase) regardless of the position of the servo actuator. In addition to the tracking position information from the conventional burst, the second pulse signal Therefore, tracking accuracy is greatly increased.
(2) According to the third and fourth aspects of the invention, the burst (for example, linear tape open servo pattern) having the first pulse signal over the entire servo pattern does not interfere with the second pulse signal. .
(3) According to the invention described in claims 5 and 6, the servo pattern comprising the burst having the first pulse signal and the second pulse signal without changing the servo track read head of the current drive device Can be reproduced, and an apparatus with high tracking accuracy can be realized without significant apparatus change.
(4) According to the invention described in claims 7 and 8, by adding the second pulse generating head to the current servo pattern forming apparatus, the cause of tracking error is eliminated without making a significant apparatus change. A high quality servo pattern can be written.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. FIG. 1 shows one servo frame of an auxiliary pulse (second pulse signal) added LTO servo pattern according to this embodiment. 1, the same parts as those in FIG. 4 are denoted by the same reference numerals.

  On both sides in the longitudinal direction (time axis direction) of each burst of A, B, C, D, a length (186 μm) equal to the interval along the line perpendicular to the tape edge between both ends of the tape width direction of each burst A to D ± 60) auxiliary pulses (second pulse signals) 10 are arranged at a predetermined distance from each burst.

 The dimensional relationship between each part of each of the bursts A to D and the auxiliary pulse 10 is as shown in the figure, and the distance between the adjacent auxiliary pulses 10 is 50.0 μm ± 0.1, 7.2 mm (length for 36 servo frames) on an average of 1 m. The average is 50.0 μm ± 0.15.

 The width of auxiliary pulse 10 (distance in the longitudinal direction of the tape) is 2.1 μm ± 0.4, the same as the width of each pulse signal (first pulse signal) of each of A to D bursts, and the virtual center line of the LTO servo pattern (tape The distance from the auxiliary pulse 10 to the leading edge of the first pulse of the A to D burst on the line parallel to the edge line is 15 μm.

 The recording of the auxiliary pulse 10 is arranged as close as possible to the upstream or downstream of the recording head portion of the current servowriter. The auxiliary pulse 10 is divided into two at a position corresponding to the center line of the LTO servo pattern, and the lower edge of the upper half auxiliary pulse 10u and the upper edge of the lower half auxiliary pulse 10b are made to coincide with each other.

 The servo read head reproduces over both the auxiliary pulses 10u and 10b, and the head height at which the reproduction outputs of both auxiliary pulses 10u and 10b are the same is set as the center line of the LTO servo pattern.

 When the cassette is loaded into the drive, the tape runs at a certain speed. The servo read head goes to find the servo track center line corresponding to the target data band. As shown in Figure 1, if the ratio of the distance Ta from the auxiliary pulse 10 to the first edge of the A burst and the distance Tb from this first edge to the next auxiliary pulse 10 is calculated and greater than 0.428571, the servo readhead will track The information that it is located above the center and located below if it is smaller is obtained.

 When the servo read head reproduces over both the auxiliary pulses 10u and 10b, the height of the actuator is displaced so that the reproduction outputs of both the auxiliary pulses 10u and 10b become the same.

 When the servo track center is found, the auxiliary pulse interval (Ta + Tb), Ta and Tb are measured. The inclination of the LTO servo pattern is defined as 6 °. However, the distance between the auxiliary pulse generating head and the LTO servo pattern generating head differs depending on the servo track writer. Therefore, the value of Ta includes the position deviation in addition to the speed fluctuation. By using Ta / Tb at this time as a target value, a track center value in consideration of the position deviation can be obtained.

 Next, consider a case where there is a speed deviation. Let the length deviation of Ta be ΔTa, and similarly the length deviation of Tb be ΔTb. ΔTa = k * Ta, ΔTb = k * Tb, and k are constants.

(Ta + δTa) / (Tb + δTb)
= (Ta + k * Ta) / (Tb + k * Tb)
= ((1 + k) * Ta) / ((1 + k) * Tb)
= Ta / Tb.

 In other words, the value of Ta / Tb is not easily affected by the speed deviation. Table 1 shows a part of Ta / Tb values when the position of the servo track center is shifted to 1 micron by making use of this fact.

 In Table 1 and FIG. 1, Hu represents the distance from the center line in the upward direction of the track width, and Hb represents the distance from the center line in the downward direction of the track width.

 As can be seen from Table 1, Ta / Tb changes by approximately 1% or more when Hu and Hb change by 1 micron. Therefore, in order to detect a tracking error of 0.1 micron, it is necessary to have a clock that can obtain four significant figures. LTO defines tolerances up to several tens of nanometers and can be detected with almost the same clock.

 Next, consider the case where the tape fluctuates in the width direction due to LTM. In FIG. 1, consider the case where the tape runs at an angle of θ. Let P be the point that intersects the first pulse of A burst at the target widthwise position Hu. When a θ-inclined line L passing through point P is drawn, the line L is a trace traced by the servo read head.

 The length corresponding to Ta is Ta * secθ, and the length corresponding to Tb is Tb * secθ. Ta * secθ / Tb * secθ = Ta / Tb and there is no effect of tilting θ. Even if the tape fluctuates in the vertical direction, the position of the auxiliary pulse does not change, so there is no influence.

 As described above, by arranging the vertical auxiliary pulse 10 and the absolute track center position in the tape servo pattern, there is an advantage that accurate tracking information can be obtained.

 FIG. 2 is a schematic diagram of the auxiliary pulse generation (recording) head 21 and the LTO servo pattern generation (recording) head 22 of the present invention. The auxiliary pulse generating head 21 of the present invention is arranged upstream of the LTO servo pattern generating head 22 of the servo pattern writer. It is preferable to arrange the head at a relatively close distance from the LTO servo pattern generating head 22, but there is no restriction of how many millimeters or less. Further, an auxiliary pulse reproducing head 24 is arranged at the front edge of the conventional LTO servo pattern generating head 22 on the tape entry side via a gap 23.

  In order to form the pattern of FIG. 1 of the present invention, an auxiliary pulse 10 is first recorded on a blank tape. The interval of the auxiliary pulse 10 varies according to the speed variation component of the conventional servo pattern writer device.

 The servo band of the variable head actuator of the drive and the fluctuation frequency band measured conventionally are 2KHz or less. For a drive running at 5.5m / s, the pitch corresponding to 2KHz is 5500mm / s / 2000s = 2.75mm. Since the interval of the auxiliary pulse is 50 μm, 2.75 mm / 0.05 mm = 55 pulses. Therefore, the fluctuation in the time axis direction may be averaged every half of 55 pulses.

 It can be said that the tape speed deviation on the auxiliary pulse generating head 21 is a deviation of the same phase, the same speed and the same displacement even if they are 55/2 pulses apart if the local tape tension is constant. Actually, this assumption is not valid because the local tape tension is affected by the guide material and the head.

  When the auxiliary pulse 10 including the speed fluctuation is recorded, passes over the auxiliary pulse reproducing head 24, and runs at the reference tape speed, the time Th after passing the reproducing head so that the positional relationship of the servo pattern shown in FIG. 1 is obtained. Record the LTO servo pattern AB burst and CD burst as usual. Write an LTO servo pattern every other auxiliary pulse.

The relationship when there is a speed fluctuation is as described above.

Since the length deviation of Ta is δTa, and similarly the length deviation of Tb is δTb, δTa = k * Ta, δTb = k * Tb, k is a constant,
(Ta + ΔTa) / (Tb + ΔTb) = (1 + k) Ta / (1 + k) / Tb = Ta / Tb.

  Here, since the speed fluctuation within one pulse interval is sufficiently smaller than 55/2 pulses, it can be said that the speed fluctuation is linear between these pulses. Therefore, the relationship of ΔTa = k * Ta and ΔTb = k * Tb is established.

  Needless to say, it is preferable that the distance between the auxiliary pulse reproducing head 24 and the LTO servo pattern generating head 22 be smaller between 1 and 55 pulses. Since the generation trigger of the time Th is the auxiliary pulse reproducing head 24, even if the auxiliary pulse generating head 21 is sufficiently separated from the auxiliary pulse reproducing head 24, there is no effect on the present invention as long as the tape speeds on both heads are equal. . However, if the speed deviation direction is in reverse phase, the correction will be reversed, which is not preferable. Therefore, the distance between the auxiliary pulse generating head 21 and the auxiliary pulse reproducing head 24 is determined within a range in which the speed deviation is substantially equal. Arrangement of guides or the like that cause tape tension fluctuation or speed fluctuation between both heads is not preferable.

  The auxiliary pattern generating head 21 may have the same structure as the LTO servo pattern generating head 22. In FIG. 2, a schematic diagram is drawn for only one servo band. Actually, a number of heads corresponding to the number of servo bands in the tape width direction are arranged at equal intervals in the tape width direction.

  The auxiliary pulse reproducing head 24 may be a laminated MR head, for example. Since the leakage flux affects the auxiliary pulse reproducing head 24 when the LTO servo pattern is magnetized, it is necessary to devise such as providing a window in the detection section. Since the tape speed of the servo pattern writer is known, it is easy to determine this window pulse.

  The positions in the tape width direction of the auxiliary pulse generating head 21, the auxiliary pulse reproducing head 24, and the LTO servo pattern generating head 22 can be easily adjusted by visualizing the developing process or the like.

 When a tape recorded with a servo pattern writer was played back with an LTO drive and PES (Position Error Signal) was measured, the spectrum shown in Fig. 3 was obtained. When the spectrum of the fluctuation of the distance between AC pulses (distance between pulses of A and C bursts) of this tape was obtained, a result almost coincident with the spectrum of FIG. 3 was obtained. In the above example, the PES was σ = 0.8 microns. From the spectrum, it is easy to see that the fluctuation component of 1KHz occupies the main component of 0.8 microns.

 The speed at which the servo pattern is written greatly affects the productivity in producing the recording medium. The faster the writing speed is, the better. However, the fluctuation of the tape increases corresponding to the speed, and the tape is regulated by the edge in order to suppress the fluctuation. However, the frequency of the disturbance on the tape due to this regulation increases with the speed. In the above example, it is around 1 KHz, but if the writing speed is further increased, the frequency becomes higher.

 In the above example, the AC pulse time difference on the servo pattern fluctuates with a spectrum centered around 1 KHz, the denominator in the PES calculation formula PES = ref-AB pulse distance / AC pulse distance fluctuates, while the numerator is magnetized. Since it is a constant value determined by the pattern, the PES deteriorates in synchronization with fluctuations in the time axis direction. Furthermore, since the frequency of 1 KHz is outside the servo band of the head actuator, the residual PES that cannot be corrected by the head actuator is at a level where normal recording / reproduction cannot be performed.

 In such a case, in the present invention of the auxiliary pulse jitter correction servo pattern method, 5500 mm / s / 1000s = 5.5 mm 5.5 mm / 0.05 = 110 pulses is sufficient for the tape longitudinal direction fluctuation at 1 KHz with the above auxiliary pulse number. Can be corrected.

 For example, in LTO-4, the PES needs to be suppressed to σ = 0.1 to 0.2 microns, which can be said to depend on the quality of the servo pattern rather than the tracking capability of the drive. Therefore, the present invention can effectively eliminate the tracking error factor caused by the servo pattern writer.

Explanatory drawing which shows the servo pattern of the linear tape of one Embodiment of this invention. The schematic diagram which shows the structure of the servo pattern writing apparatus of the linear tape of one Embodiment of this invention. The characteristic figure of frequency vs. PES for explaining the influence on the PES by the tape speed deviation. Explanatory drawing which shows the conventional LTO servo pattern. Explanatory drawing which shows the peak jitter of an LTO servo pattern. The characteristic figure which shows the fluctuation | variation of the time-axis direction of the distance between bursts in a LTO servo pattern.

Explanation of symbols

10 ... Auxiliary pulse, 10u ... Upper auxiliary pulse, 10b ... Lower auxiliary pulse, A to D ... Burst, 21 ... Auxiliary pulse generation head, 22 ... LTO servo pattern generation head, 23 ... Gap, 24 ... Auxiliary pulse regeneration head.

Claims (8)

A linear tape in which a servo band having a plurality of servo tracks along the magnetic tape longitudinal direction and a data band having a plurality of recording tracks along the magnetic tape longitudinal direction are alternately formed in the tape width direction,
Each of the plurality of servo bands formed on the servo band has a predetermined width in the longitudinal direction of the magnetic tape, is inclined at a predetermined angle with respect to a line perpendicular to the tape edge, and is formed at predetermined intervals in the tape longitudinal direction. Bursts having a first pulse signal are formed at predetermined intervals in the longitudinal direction of the tape;
A second pulse signal that is parallel to the line orthogonal to the tape edge and has a length approximately equal to the distance along the line orthogonal to the tape edge between both ends in the tape width direction of the first pulse signal. A linear tape comprising servo patterns formed at predetermined intervals from the burst on both sides of the burst in the longitudinal direction of the tape.   The second pulse signal is divided into two in the tape width direction on a virtual center line of a servo pattern parallel to the tape edge, and one of the divided signals is the first pulse signal with respect to the other signal. The linear tape according to claim 1, wherein the linear tape comprises a set of pulse signals that are formed at a distance equal to the width of the tape and shifted in the longitudinal direction of the tape.   The interval between the first pulse signal of the burst and the second pulse signal adjacent thereto is the interval between the two adjacent second pulse signals on the virtual center line of the servo pattern parallel to the tape edge. 2. The linear tape according to claim 1, wherein the linear tape is 15 μm when 1 m average is 50 μm ± 0.1 and 7.2 mm average is 50 μm ± 0.15.   The interval between the first pulse signal of the burst and the second pulse signal adjacent thereto is the interval between the two adjacent second pulse signals on the virtual center line of the servo pattern parallel to the tape edge. 3. The linear tape according to claim 2, wherein the linear tape is 15 μm when 1 m average is 50 μm ± 0.1 and 7.2 mm average is 50 μm ± 0.15. 4. A drive device for reproducing the linear tape according to claim 2,
The servo signal reproducing head reproduces the servo pattern along the servo track, and performs tracking servo control based on the difference between the reproduced signal of one signal of the second pulse signal and the reproduced signal of the other signal. A linear tape drive device characterized by that.   The drive device reproduces the servo pattern along a servo track by a servo signal reproduction head, and reproduces a first pulse signal of a burst adjacent to the second pulse signal from a reproduction time of the second pulse signal. Tracking servo control is performed based on the ratio between the time Ta until the time and the time Tb from the reproduction time of the first pulse signal to the reproduction time of the second pulse signal to be reproduced next. The linear tape drive device according to claim 5. An apparatus for writing a servo pattern of the linear tape according to claim 1,
A first pulse generating head for generating a first pulse signal of the burst, which is disposed at a predetermined interval along the traveling direction of the magnetic tape;
A second pulse generating head for generating the second pulse signal;
A linear tape servo comprising: a second pulse reproducing head disposed between the first pulse generating head and the second pulse generating head for reproducing the second pulse signal. Pattern writing device. An apparatus for writing a servo pattern of the linear tape according to claim 2,
A first pulse generating head for generating a first pulse signal of the burst, which is disposed at a predetermined interval along the traveling direction of the magnetic tape;
A second pulse generating head for generating the second pulse signal;
A linear tape servo comprising: a second pulse reproducing head disposed between the first pulse generating head and the second pulse generating head for reproducing the second pulse signal. Pattern writing device.

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