Toshiba Prototypes 30 GB HD DVD Disc. (Recordable)

Discussion in 'DVD Video' started by Allan, Jul 20, 2005.

  1. Allan

    Allan Guest

    Toshiba have presented recording and readout results of their proposed
    HD DVD-R DL, the company's new double layer HD DVD-R disc with a
    capacity of 30 GB, at the ISOM/ODS '05 event.

    The International Symposium on Optical Memory and Optical Data Storage
    was held this year (July 10-14) at the Hyatt Regency in Waikiki
    Honolulu, Hawaii.

    Toshiba revealed details of the prototype, following a press meeting
    in May 2005, at which the company only showed its playback signals.
    Along with the development of an organic dye for the recording layer,
    the company also established a manufacturing process requiring lower
    costs than the previous DVD-R DL manufacturing process.

    To make an HD-DVD disc double-layered, the company needed to reduce
    the thickness of the Ag reflection layer, located close to the optical
    head so thatthe laser beam can reach the other layer (Layer 0) more
    easily. However, the thinner the Ag reflection layer gets, which also
    works as a heat sink, the weaker its heat releasing effects become;
    and therefore the larger the heat interferences between recorded marks
    grow. Toshiba overcame these problems with an organic dye with good
    heat conductivity, newly developed in conjunction with raw material
    manufacturers. This dye is a low to high polarity dye, which increases
    reflection when exposed.

    Conventional 2P (photopolymer) process is used to form the middle
    layer. In existing double layer DVD-R media, disposable polyolefin
    stampers are used to transcribe the recording layer's concavities and
    convexities onto the photopolymer. Toshiba has employed 0.6 mm-thick,
    polycarbonate injection molded stampers instead of the polyolefin
    stampers. As a result, polycarbonate once used in stampers can be
    reused as alternative dummy substrates.

    The Blu-Ray Response

    At the same time, Philips showcased the latest developments and
    results of its research work on behalf of the rival Blu-Ray camp. The
    Philips research team announced their successfull testing on BD-R
    (Blu-Ray Recordable) recording procedures.

    Unlike the BD-RE (Blu-Ray Rewritable) disc which is based on the
    phase-change layer technology, and alternatively to the use of a dye
    layer, Philips proposed the usage of a Cu/ Si bilayer to be applied as
    the recording medium in a write-once Blu-ray Disc (BD-R).

    The write process basically comprises the formation of a CuSi alloy
    containing 25?30 at. % Si, while any excess Si is left behind as
    unreacted film. Auger analyses of the laser-written layers indicate
    that recording consists primarily of the diffusion of Si into Cu.

    The results coming from Philips labs indicate that this technology
    offers adequate results in terms of disc readability and high
    recording speeds. The very low jitter levels of typically 4%, proved
    to be achievable with equally thick films of Cu and Si as recording
    medium.

    Philips has successfully tested first recordings on Cu/Si bilayer BD-R
    media at 1x-7x speeds (25GB, single layer). Note that 7x BD-R speed
    equals 10x for DVD and 30x for CD. The results indicate that the
    shortest possible recording time was given at a rotational speed fixed
    at 10800 rpm, which is equal to 200 km/h! At the same time, the linear
    velocity at 7x is aproximatelly 35m/sec. To make things clear, this
    means that 25GB of data can be recorded at 7x in just 14 minutes.

    The most suitable writing strategy for 7x recording, according to
    Philips, should be the so-called "Castle Write Strategy". Hence, for
    speeds of 1X-2X it will use the improved (n-1) writing strategy and
    for 4X - 7X the Castle writing strategy just mentioned.








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    - Neil Stephenson, _Cryptonomicon_
     
    Allan, Jul 20, 2005
    #1
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  2. Allan

    Alpha Guest

    Thanks for this interesting update. It is apparent that these formats,
    especially Blu Ray write once, are still being developed. I wonder if the
    products can be brought on line in order to meet their published deadlines
    (I think not).
     
    Alpha, Jul 20, 2005
    #2
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