1. A method of encoding a plurality of tracks of data for storage on a tape data storage medium, said method characterized by comprising:
for each of said plurality of data tracks written to said tape data storage medium, writing within said data track, a preamble region (702) which precedes a user data region, said preamble region having a preamble data sequence having a power spectrum (900) substantially similar to a power spectrum of a substantially random data.
2. The method as claimed in claim 1, wherein said preamble data sequence has a power spectrum having no significant troughs over a frequency band extending between first and second 6 dB power levels, each side of a peak value.
3. The method as claimed in claim 1 or 2, wherein a said preamble region (702) comprises between 800 and 900 bits.
4. The method as claimed in any one of the preceding claims, wherein said preamble data sequence has a power spectrum characteristic substantially similar to a power spectrum characteristic of the following byte stream;
b3, d2, b8, 83, 67, a5, 71, 06, cf, 4a, e2, 0d, 9e, 95, c4, 1b, 3d, 2b, 88, 36, 7a, 57, 10, 6c, f4, ae, 20, d9, e9, 5c, 41, b3, d2, b8, 83, 67, a5, 71, 06, cf, 4a, e2, 0d, 9e, 95, c4, 1b, 3d, 2b, 88, 36, 7a, 57, 10, 6c, f4, ae, 20, d9, e9, 5c, 41, b3, d2, b8, 83, 67, a5, 71, 06, cf, 4a, e2, 0d, 9e, 95, c4, 1b, 3d, 2b, 88, 36, 7a, 57.
5. The method as claimed in any one of the preceding claims, wherein said preamble data sequence comprises bits, which when written to tape each occupy a length of the order of 100 to 140 nanometers per bit.
6. The method as claimed in any one of the preceding claims, wherein said preamble data sequence has a distribution of density of transitions having valid phase information which is free of peaks of more than or 6 transitions.
7. The method as claimed in any one of the preceding claims, wherein said plurality of data tracks are written across a width of said tape data storage medium in a direction transverse to a main length of said tape data storage medium.
8. The method as claimed in any one of the preceding claims, wherein said preamble data sequence is 8-10 coded and a resulting coded preamble data has a power spectrum substantially similar to a power spectrum of an 8-10 modulation coding convolved with a power spectrum of a substantially random data.
9. The method as claimed in any one of the preceding claims, wherein said preamble data sequence has at least 8 bits corresponding to a 2T transition pattern, where a 1T transition comprises a minimum spacing between pulse transitions.
10. A method of encoding a plurality of tracks of data for storage on a tape data storage medium, said method characterized by comprising:
for each of said plurality of data tracks written to a tape data storage medium, writing within said data track a preamble region having a preamble data sequence having a power spectrum substantially similar to a power spectrum of a 8-10 modulation coding convolved with a power spectrum of a substantially random data.
11. A method of reading a data stream from a tape data storage medium, said method comprising the steps of:
reading a preamble data, said preamble data comprising a data stream having a power spectrum equivalent to a power spectrum of an 8-10 modulation encoded byte stream convolved with a power spectrum of a substantially random bit stream; and
synchronising to said read preamble data stream.
12. The method as claimed in claim 11, wherein said data stream comprises a byte stream having a power spectrum equivalent to a power spectrum of an 8-10 coding convolved with a power spectrum of a substantially random data.
13. An encoder device for encoding a plurality of tracks of data for storage on a tape data storage medium, said encoder device comprising means for generating a byte stream as claimed in any one of the preceding claims.
14. An apparatus for encoding a plurality of tracks of data for storage on a tape data storage medium, said apparatus comprising:
a write circuit for writing said plurality of data tracks to a tape data storage medium, said write circuit arranged for writing on said data track, a preamble region (702) which precedes a user data region, said preamble region having a preamble data sequence having a power spectrum (900) substantially similar to a power spectrum of a substantially random data.
15. The apparatus as claimed in claim 14, wherein said write channel is arranged to write between 800 and 900 bits of said preamble data sequence on each of said plurality of tracks.
16. The apparatus as claimed in claim 14 or 15, arranged to write a preamble data sequence having a power spectrum characteristic substantially similar to a power spectrum characteristic of the following byte stream;
b3, d2, b8, 83, 67, a5, 71, 06, cf, 4a, e2, 0d, 9e, 95, c4, 1b, 3d, 2b, 88, 36, 7a, 57, 10, 6c, f4, ae, 20, d9, e9, 5c, 41, b3, d2, b8, 83, 67, a5, 71, 06, cf, 4a, e2, 0d, 9e, 95, c4, 1b, 3d, 2b, 88, 36, 7a, 57, 10, 6c, f4, ae, 20, d9, e9, 5c, 41, b3, d2, b8, 83, 67, a5, 71, 06, cf, 4a, e2, 0d, 9e, 95, c4, 1b, 3d, 2b, 88, 36, 7a, 57.
17. The apparatus as claimed in any one of claims 14 to 16, wherein said write channel is arranged to write bits of data to said tape, wherein each said bit occupies a length of the order 100 to 140 nanometers per bit.
18. The apparatus as claimed in any of claims 14 to 17, arranged to write a said preamble data sequence having a distribution of transitions containing phase information validly useable by a timer circuit which is free of peaks of density of more than or 6 transitions from a mean value.
19. The apparatus as claimed in any one of claims 14 to 18, arranged to write said plurality of data tracks across a width of said tape data storage medium in a direction transverse to a main length of said tape data storage medium.
20. The apparatus as claimed in any one of claims 14 to 19, comprising an 8-10 encoder for encoding said preamble data sequence, to result in an 8-10 encoded preamble data sequence having a power spectrum substantially similar to a power spectrum of an 8-10 coding convolved with a power spectrum of a substantially random data.
21. An apparatus for reading a data stream from a tape data storage medium, said apparatus comprising:
means for reading a preamble data sequence, said preamble data sequence comprising a data stream having a power spectrum equivalent to a power spectrum of a user data.
22. An apparatus for reading and writing a data sequence, said data sequence comprising:
a preamble data region and;
a user data region;
wherein said preamble data region comprises a byte stream having a power spectrum substantially similar to a power spectrum of said user data in said user data region.
23. The apparatus as claimed in claim 22, wherein said byte stream comprises a byte stream having a power spectrum characteristic substantially similar to a power spectrum characteristic of the following byte stream:
b3, d2, b8, 83, 67, a5, 71, 06, cf, 4a, e2, 0d, 9e, 95, c4, 1b, 3d, 2b, 88, 36, 7a, 57, 10, 6c, f4, ae, 20, d9, e9, 5c, 41, b3, d2, b8, 83, 67, a5, 71, 06, cf, 4a, e2, 0d, 9e, 95, c4, 1b, 3d, 2b, 88, 36, 7a, 57, 10, 6c, f4, ae, 20, d9, e9, 5c, 41, b3, d2, b8, 83, 67, a5, 71, 06, cf, 4a, e2, 0d, 9e, 95, c4, 1b, 3d, 2b, 88, 36, 7a, 57.
24. The apparatus as claimed in claim 22 or 23, further comprising an 8-10 modulation coder for coding said preamble data and said user data, wherein said coded preamble data has a power spectrum substantially similar to a power spectrum of said user data convolved with a power spectrum of said modulation coding.
25. The apparatus as claimed in any one of claims 22 to 24, capable of writing a preamble data sequence having a last 8 bits corresponding to a 2T transition patter.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A backlight apparatus, comprising:
a guiding element having a bottom surface and an emitting surface, the bottom surface having a plurality of reflective patterns, each reflective pattern being composed of a concavity and a convexity, the concavity being disposed at a rim of the convexity; and
at least one light source disposed on at least one lateral sides of the guiding element for emitting light to the guiding element.
2. The backlight apparatus according to claim 1, wherein the concavity is of a ring shape and the shape is substantially the same as the shape of the rim of the convexity.
3. The backlight apparatus according to claim 1, wherein at least one ring part are disposed mutually connected in sequence from the rim of the concavity toward outside.
4. The backlight apparatus according to claim 3, wherein the ring part is a convexity of a ring shape or a concavity of a ring shape.
5. The backlight apparatus according to claim 1, wherein the shape of the concavity is a circular ring, an elliptic ring, a rectangular ring or a polygon ring.
6. The backlight apparatus according to claim 1, wherein the bottom of the concavity is a rough surface.
7. The backlight apparatus according to claim 1, wherein the surface of the convexity is a rough surface.
8. The backlight apparatus according to claim 7, wherein the roughness of the concavity is from Ra 0.05 mm to Ra 5.0 mm and the depth thereof is from 0.001 mm to 0.5 mm, the roughness of the convexity being from Ra 0.05 mm to Ra 5.0 mm and the height thereof being from 0.001 mm to 0.5 mm and the diameter thereof being from 0.03 mm to 2.0 mm.
9. A backlight apparatus, comprising:
a guiding element having a bottom surface and a emitting surface, the bottom surface having a plurality of reflective patterns, each reflective pattern being composed of a concavity and a convexity, the convexity being disposed at a rim of the concavity; and
at least one light source disposed on at least one lateral sides of the guiding element for emitting light to the guiding element.
10. The backlight apparatus according to claim 9, wherein the convexity is of a ring shape and the shape is substantially the same as the shape of the rim of the concavity.
11. The backlight apparatus according to claim 9, wherein the shape of the convexity is a circular ring, an elliptic ring, a rectangular ring or a polygon ring.
12. The backlight apparatus according to claim 9, wherein the bottom of the concavity is a rough surface.
13. The backlight apparatus according to claim 9, wherein the surface of the convexity is a rough surface.
14. The backlight apparatus according to claim 9, wherein at least one ring part are disposed mutually connected in sequence from the rim of the convexity toward outside.
15. The backlight apparatus according to claim 14, wherein the ring part is a convexity of a ring shape or a concavity of a ring shape.
16. A backlight apparatus, comprising:
a guiding element having a bottom surface and a emitting surface, the bottom surface having a plurality of reflective patterns, each reflective pattern being composed of a concavity and a concave ring disposed at a rim of the concavity; and
at least one light source disposed on at least one lateral sides of the guiding element for emitting light to the guiding element.
17. A backlight apparatus, comprising:
a guiding element having a bottom surface and a emitting surface, the bottom surface having a plurality of reflective patterns, each reflective pattern being composed of a convexity and a convex ring disposed at a rim of the convexity; and
at least one light source disposed on at least one lateral sides of the guiding element for emitting light to the guiding element.