Method of tape attachment to a tape cartridge reel

A method of attaching a tape having longitudinal edges to a tape cartridge reel includes cutting an end of the tape non-perpendicularly to the longitudinal edges laterally across the width of the tape. The end of the tape is then attached to the tape cartridge reel. The method may also include cutting an end of the tape such that at least two of the laterally spaced apart servo stripes running longitudinally along the tape are cut at different longitudinal positions along the tape. The method may further include cutting the tape end such that at least two of the laterally spaced apart data tracks running longitudinally along the tape are cut at different longitudinal positions along the tape.

TECHNICAL FIELD 
The present invention relates generally to tape cartridges and, more 
particularly, to an improved method of attaching magnetic tape to the 
reels of a magnetic tape cartridge. 
BACKGROUND ART 
Typically, to attach magnetic tape to the reels of a magnetic tape 
cartridge or cassette, the tape is cut perpendicularly to its longitudinal 
edges laterally across its width at each end. The ends are then attached 
to the reels of the cartridge and the tape is wrapped around the reels. 
Ideally, the tape wraps are perfectly smooth. In reality, a discontinuity 
exists on each reel along the lateral interface where the end of the tape 
attaches to the reel. The discontinuity causes an impression or imprint in 
the first few hundred tape wraps. 
Data written on the longitudinally extending, parallel data tracks of the 
tape may not be consistently retrievable because the impression affects 
all of the data tracks at the same lateral location at the same time. This 
results in data errors. The severity of the errors may be such that the 
error correction code written on the data tracks to protect the data 
tracks cannot recover the data. 
Similarly, servo information written on the longitudinally extending, 
parallel servo tracks of the tape may also not be consistently retrievable 
because the impression affects all of the servo tracks at the same lateral 
location at the same time. Thus, the servo redundancy cannot be used to 
recover the servo information. This results in servo errors and subsequent 
incorrect lateral positioning of the tape head with respect to the tape. 
Tape impressions are a continuing problem in the data storage industry. Not 
using the portion of the tape with impressions results in wasted data 
storage capability and wasted time, as the tape must always be advanced 
past the unusable portions. 
What is needed is a method of attaching tape to the reels of a cartridge 
such that impressions do not affect all of the data tracks and servo 
stripes at the same lateral location at the same time. The needed method 
must take advantage of the error correction code and servo redundancy such 
that data and servo information from the tape wraps may be consistently 
retrievable regardless of impressions. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a method 
of attaching tape to the reels of a cartridge such that data and servo 
errors caused by impressions are spread out longitudinally along the tape. 
It is another object of the present invention to provide a method of 
attaching tape to the reels of a cartridge such that impressions only 
corrupt some of the data tracks at any one time while a tape head is 
reading the tape. 
It is a further object of the present invention to provide a method of 
attaching tape to the reels of a cartridge such that impressions only 
corrupt some of the servo tracks at any one time while a tape head is 
reading the tape. 
It is still another object of the present invention to provide a method of 
attaching tape to the reels of a cartridge which includes cutting the tape 
ends to be attached to the reels non-perpendicularly to the longitudinal 
edges of the tape laterally across the width of the tape. 
It is still a further object of the present invention to provide a method 
of attaching tape to the reels of a cartridge which includes cutting the 
tape ends to be attached to the reels as a function of the correctional 
capability of the error correction code and the redundant servo 
information. 
In carrying out the above objects and other objects, the present invention 
provides a method of attaching a tape having longitudinal edges to a tape 
cartridge reel. The method includes cutting an end of the tape 
non-perpendicularly to the longitudinal edges laterally across the width 
of the tape. The end of the tape is then attached to the tape cartridge 
reel. 
Further, in carrying out the above objects and other objects, the present 
invention provides another method of attaching a tape to a tape cartridge 
reel. The tape includes longitudinal edges and laterally spaced apart 
servo stripes running longitudinally along the tape. This method includes 
cutting an end of the tape such that at least two of the servo stripes are 
cut at different longitudinal positions along the tape. The end of the 
tape is then attached to the tape cartridge reel. 
The tape may include laterally spaced apart data tracks running 
longitudinally along the tape. Cutting an end of the tape may then also 
include cutting the end such that at least two data tracks are cut at 
different longitudinal positions along the tape. Thus, the end of the tape 
is cut non-perpendicularly to its longitudinal edges laterally across its 
width to cut the at least two servo stripes and the at least two data 
tracks at different longitudinal positions along the tape. 
In accordance with the methods of the present invention, a tape cartridge 
is also provided. 
These and other features, aspects, and embodiments of the present invention 
will become better understood with regard to the following description, 
appended claims, and accompanying drawings.

BEST MODES FOR CARRYING OUT THE INVENTION 
Referring now to FIG. 1, magnetic tape 10 having parallel, laterally spaced 
apart data bands 12(a-d) running longitudinally along the tape is shown. 
Tape 10 also includes parallel, laterally spaced apart servo stripes 
14(a-e) interposed between data bands 12(a-d) and running longitudinally 
along the tape. Tape 10 includes longitudinal edges 15(a-b) separated by a 
width (W) of the tape. Data bands 12(a-d) and servo stripes 14(a-e) 
preferably run from end 17 to end 19 of tape 10. However, tape 10 may have 
an area at each end that does not have any data bands and servo stripes. 
As shown in FIG. 2, tape 10 includes four data bands 12(a-d). Each of data 
bands 12(a-d) includes nine sets of eight data tracks for a total of 
seventy-two data tracks (not specifically shown). A movable tape head is 
shown in an upper position 24a in an upper band 23 of tape 10 adjacent to 
the tape. Similarly, the tape head is shown in a lower position 24b in a 
lower band 25 of tape 10 adjacent to the tape. The tape head is movable 
between the upper and lower positions 24(a-b) and is in only one of the 
positions at a given time. 
The tape head includes two sets of eight read/write elements (shown in FIG. 
7) to read from and write to one set of data tracks in each of data bands 
12a and 12b simultaneously in upper position 24a. Thus, one set of eight 
data tracks in each of data bands 12a and 12b are active at one time when 
the tape head is in upper position 24a. Similarly, the tape head can read 
from and write to one set of data tracks in each of data bands 12c and 12d 
simultaneously in lower position 24b. Thus, one set of eight data tracks 
in each of data bands 12c and 12d are active at one time when the tape 
head is in lower position 24b. Thus, a total of sixteen data tracks are 
active at any one time when the tape head is in either upper or lower 
positions 24(a-b). 
The tape head is laterally movable across tape 10 between different sets of 
data tracks in data bands 12(a-d). A tape head controller (not 
specifically shown) controls the tape head to laterally move it across 
upper and lower bands 23 and 25 of tape 10. 
Referring now to FIG. 3, each servo stripe 14(a-e) includes a frame 16. A 
first frequency signal 18 is written onto frame 16. An erase frequency 
signal 20 is written over first frequency signal 18 in a predetermined 
pattern to define longitudinally extending servo tracks 22(a-e). The 
predetermined pattern is preferably a checkerboard pattern of erase 
frequency signal rectangles 20 written over first frequency signal 18 
parallel to longitudinal edges 15a and 15b of tape 10 as shown in FIG. 3. 
Servo tracks 22(a-e) are defined by the horizontal interfaces between 
erase frequency signal rectangles 20. Of course, any pattern of erase 
frequency signals may be used to define servo tracks. 
The tape head includes servo read elements 26(a-c) to read respective servo 
tracks 22(a-c) when the tape head is in upper position 24a. Similarly, 
servo read elements 26(a-c) read respective servo tracks 22(c-e) when the 
tape head is in lower position 24b. As tape 10 moves across the tape head, 
each servo read element 26(a-c) reads a corresponding servo track 22(a-e) 
and generates a position error signal. The position error signals are 
indicative of the lateral positions of servo read elements 26(a-c) with 
respect to the servo tracks. The position error signals are also 
indicative of the lateral position of the tape head with respect to the 
data tracks. Servo read elements 26(a-c) provide the position error 
signals to a servo loop for use by the tape head controller (not 
specifically shown). Tape head controller moves the tape head to move 
servo read elements 26(a-c) as a function of the position error signals to 
enable precise servo track following. 
Tape 10 has multiple servo stripes 14(a-e) laterally spaced across the 
width (W) of the tape to improve the accuracy with which the servo loop 
operates. The position error signals generated by servo read elements 
26(a-c) may be concurrently read and averaged. The position of the tape 
head is maintained by the servo loop in response to the average, rather 
than the position error signal from any one servo read element. Such 
redundancy makes the servo loop less susceptible to error or failure due 
to an error by any one servo read element. Ideally, the servo loop will 
recognize corrupted position error signals and only use the redundant 
position error signals. 
Referring now to FIG. 4, tape 10 is cut in accordance with the present 
invention into two ends 28 and 30. Each of ends 28 and 30 is cut 
non-perpendicularly to longitudinal edges 15(a-b) laterally across the 
width (W) of tape 10. Thus, at least two of servo stripes 14(a-c) in upper 
band 23 and at least two servo stripes 14(c-e) in lower band 25 are cut at 
different longitudinal positions along tape 10. Similarly, at least two 
data tracks in each of upper and lower bands 23 and 25 are cut at 
different longitudinal positions along tape 10. 
Referring now to FIG. 5A, end 28 of tape 10 is attached to a hub 32 of a 
reel of a tape cartridge. End 28 is attached to hub 32 by initially 
placing a liquid on the hub and then wrapping tape 10 around the hub as 
known to those of ordinary skill in the art. As tape 10 is wrapped around 
hub 32 an impression 33 forms where end 28 is attached to the hub. 
Impression 33 mirrors the outline of end 28. 
Similarly, as shown in FIG. 5B, end 30 of tape 10 is attached to a second 
hub 34 of a second reel of a tape cartridge. As tape 10 is wrapped around 
hub 34 an impression 35 forms where end 30 is attached to hub 34. 
Impression 35 mirrors the outline of end 30. 
Referring now to FIG. 6A, the tape head is positioned to read a portion of 
tape 10 having impression 33 at a given instant of time as the tape is 
moving across the tape head. Impression 33 affects servo stripes 14(a-e) 
at different longitudinal positions of tape 10. As a result, some of servo 
stripes 14(a-e) are affected by impression 33 when the tape head is 
positioned in either upper or lower positions 24(a-b) to read these servo 
stripes as tape 10 moves at the given instant of time. 
For instance, as shown in FIG. 6A, when the tape head is in upper position 
24a, servo read elements 26b and 26c can read their respective servo 
stripes 14b and 14c without being affected by impression 33. Servo read 
elements 26b and 26c do not read any tape distortion because the portions 
of the servo stripes being read are relatively smooth. Similarly, when the 
tape head is in lower position 24b, servo read elements 26(a-c) can read 
their respective servo stripes 14(c-e) without being affected by 
impression 33. 
However, the portion of servo stripe 14a read by servo read element 26a 
when the tape head is in upper position 24a is affected by impression 33 
at the given instant of time. This is shown in FIG. 6A by impression 33 
running through servo read element 26a. Consequently, servo information 
read by servo read element 26a may be in error. 
An advantage of the present invention is that because the servo information 
is redundant the tape head controller can use the other unaffected servo 
information, i.e., servo information from servo read elements 26(b-c), to 
maintain the proper lateral position of the tape head with respect to tape 
10. Thus, as long as one of servo stripes 14(a-c) in upper band 23 of tape 
10 is unaffected by impression 33 at a given instant of time, the proper 
positioning of the tape head in the upper band can be maintained. 
Likewise, as long as one of servo stripes 14(c-e) in lower band 25 of tape 
10 is unaffected by impression 33 in a given instant of time, the proper 
positioning of the tape head in the lower band can be maintained. As a 
result, end 28 of tape 10 is cut such that only part of the servo 
information in each band of tape may be corrupted by an impression at any 
one time. 
Referring now to FIG. 6B, tape 10 has moved in the next instant of time 
along the direction of the tape travel from its position shown in FIG. 6A. 
Now, when the tape head is in upper position 24a, servo read elements 26a 
and 26b can read their respective servo stripes 14a and 14b without being 
affected by impression 33. Similarly, when the tape head is in lower 
position 24b, servo read elements 26(a-c) can read their respective servo 
stripes 14(c-e) without being affected by impression 33. 
However, the portion of servo stripe 14c read by servo read element 26c 
when the tape head is in upper position 24a is affected by impression 33 
at the given instant of time. This is shown in FIG. 6B by impression 33 
running through servo read element 26c. Consequently, servo information 
read by servo read element 26c may be in error. As before, the tape head 
controller can use the other unaffected redundant servo information to 
maintain the proper lateral positioning of the tape head with respect to 
upper band 23 of tape 10. 
Each of ends 28 and 30 of tape 10 is cut non-perpendicularly to 
longitudinal edges 15(a-b) laterally across the width (W) of the tape such 
that all of servo stripes 14(a-e) in each of upper and lower bands 23 and 
25, servo stripes 14(a-c) in the upper band and servo stripes 14(c-e) in 
the lower band, are not affected by an impression at the same longitudinal 
position along the tape at the same time. As used herein, the term 
non-perpendicular cut means a cut in the shape of a chevron, a "V" on 
either of its side, a straight diagonal, and the like. Attaching 
non-perpendicularly cut ends to the hubs of a cartridge ensures that the 
impressions formed as the tape is wrapped around the hubs only corrupts a 
part of the servo information at any one time. 
Referring now to FIG. 7, a set of data tracks 36 longitudinally extending 
along data band 12a is shown. As stated above, each of the data bands 
12(a-d) include nine sets of data tracks with each set having eight data 
tracks. Typically, each set includes the same number of data tracks as the 
number of read/write elements used for that data band in a tape head. In 
operation, read/write elements 38(a-h) of the tape head are in parallel 
with data tracks 36 and the tape head may concurrently read from and write 
to the data tracks. The tape head provides the serially read data from 
data tracks 36 to a processor (not specifically shown) which processes the 
data and puts it in a proper format. 
The set of data tracks 36 includes error correction code (ECC) areas 38. 
ECC areas 38 contain error correction coding used for correcting corrupted 
data read from data tracks 36. ECC areas 38 can correct corrupted data as 
long as the severity of the data errors are within limits. For simplicity, 
ECC area 38 is shown in FIG. 7 as extending laterally across all of data 
tracks 36 at given longitudinal positions of tape 10. For this simplified 
case, the severity of the data errors is outside of the acceptable limit 
when the data in data tracks 36 is corrupted at the same longitudinal 
position along tape 10. 
As shown in FIG. 7, tape 10 is cut such that impression 40 affects at least 
two data tracks 36 in the set at different longitudinal positions along 
the tape. Thus, impression 40 formed from the cut end of the tape does not 
corrupt all of the data tracks 36 at any one time when the tape head is 
positioned to read the data tracks as tape 10 moves. 
Cutting the tape to longitudinally spread out any servo errors caused by an 
impression also longitudinally spreads out any data errors caused by the 
impression. Because the data errors are spread out longitudinally, the 
error correction code written onto the data tracks may recover the data 
when an error occurs. 
Typically, the ECC is intimately mixed with the data of data tracks 36 such 
that it is longitudinally and laterally spread about the data tracks. The 
ECC may also be distributed across all of the data bands that are 
concurrently used. This alone may be sufficient to prevent the data error 
caused by perpendicularly cut ends from being outside of the acceptable 
limit. In any event, the distribution of the ECC should be designed with 
knowledge of the likely tape defects. Tape defects typically include 
longitudinal scratches in the tape as well as the impression caused by the 
imprint of the ends. 
Thus it is apparent that there has been provided, in accordance with the 
present invention, a method of attaching a tape to a tape cartridge reel 
that fully satisfies the objects, aims, and advantages set forth above. 
While the present invention has been described in conjunction with 
specific embodiments thereof, it is evident that many alternatives, 
modifications, and variations will be apparent to those skilled in the art 
in light of the foregoing description.