LS-R
Encyclopedia
LS-R, or the Layer-Selection-Type Recordable Optical Disk, is the term coined by Hitachi
in 2003 for a next-generation optical disc
technology which allows much larger data storage densities than DVD
, HD DVD
or Blu-ray Disc
, by allowing the use of a large number of data layers in a single disc. In previous optical disc technologies, only a relatively small number of data layers can be incorporated in a single disc, since the reflections from the different layers interfere with each other. However, in LS-R, only the layer of interest generates a reflection, meaning that a very large number of layers can theoretically be stacked in the same disc. This feat is accomplished by an electronic "selection" mechanism, whereby each data layer is coated with electrodes and only the electrodes associated with the layer of interest are activated. This activation changes the "selected" data layer from being transparent to being reflective or opaque, thus it can be addressed.
or an organic material to accomplish the optical change. A two-layer feasibility prototype has been demonstrated, and it was estimated that a 20-layer CD-sized disc could provide 1 terabyte
of data capacity. Electrical activation of layers has been achieved with transparent ITO
electrodes, and a contactless power supply
has been developed in order to allow long-term operation (given that the disc is spinning at several thousand RPM).
variant), or because it can not be made to be economically viable. The need for the disc to be meticulously constructed from many layers of different materials, and the need for the drive to be able to electrically address each layer specifically, may make this solution too expensive for commercialization.
In the next generation LS-R may compete with other next-generation optical disc format such as the Holographic versatile disc
and Protein-coated disc
formats.
Hitachi, Ltd.
is a Japanese multinational conglomerate headquartered in Marunouchi 1-chome, Chiyoda, Tokyo, Japan. The company is the parent of the Hitachi Group as part of the larger DKB Group companies...
in 2003 for a next-generation optical disc
Optical disc
In computing and optical disc recording technologies, an optical disc is a flat, usually circular disc which encodes binary data in the form of pits and lands on a special material on one of its flat surfaces...
technology which allows much larger data storage densities than DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
, HD DVD
HD DVD
HD DVD is a discontinued high-density optical disc format for storing data and high-definition video.Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format...
or Blu-ray Disc
Blu-ray Disc
Blu-ray Disc is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs being the norm for feature-length video discs...
, by allowing the use of a large number of data layers in a single disc. In previous optical disc technologies, only a relatively small number of data layers can be incorporated in a single disc, since the reflections from the different layers interfere with each other. However, in LS-R, only the layer of interest generates a reflection, meaning that a very large number of layers can theoretically be stacked in the same disc. This feat is accomplished by an electronic "selection" mechanism, whereby each data layer is coated with electrodes and only the electrodes associated with the layer of interest are activated. This activation changes the "selected" data layer from being transparent to being reflective or opaque, thus it can be addressed.
Technology
In the Hitachi implementation, LS-R technology utilizes an electrochromic film, for example of tungsten oxideTungsten oxide
Tungsten has several oxidation states, and therefore oxides:*Tungsten oxide*Tungsten oxide, also known as tungsten dioxide*Tungsten oxide, also known as tungsten trioxide...
or an organic material to accomplish the optical change. A two-layer feasibility prototype has been demonstrated, and it was estimated that a 20-layer CD-sized disc could provide 1 terabyte
Terabyte
The terabyte is a multiple of the unit byte for digital information. The prefix tera means 1012 in the International System of Units , and therefore 1 terabyte is , or 1 trillion bytes, or 1000 gigabytes. 1 terabyte in binary prefixes is 0.9095 tebibytes, or 931.32 gibibytes...
of data capacity. Electrical activation of layers has been achieved with transparent ITO
Indium tin oxide
Indium tin oxide is a solid solution of indium oxide and tin oxide , typically 90% In2O3, 10% SnO2 by weight. It is transparent and colorless in thin layers while in bulk form it is yellowish to grey...
electrodes, and a contactless power supply
Power supply
A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...
has been developed in order to allow long-term operation (given that the disc is spinning at several thousand RPM).
Commercial product
No plans or timeline for the development of a commercial product have been released. It is possible that this technology, while interesting, will remain in the realms of research, either because it is superseded by an alternative technology (such as holographic storage or another 3D optical data storage3D optical data storage
3D optical data storage is the term given to any form of optical data storage in which information can be recorded and/or read with three dimensional resolution ....
variant), or because it can not be made to be economically viable. The need for the disc to be meticulously constructed from many layers of different materials, and the need for the drive to be able to electrically address each layer specifically, may make this solution too expensive for commercialization.
In the next generation LS-R may compete with other next-generation optical disc format such as the Holographic versatile disc
Holographic Versatile Disc
The Holographic Versatile Disc is an optical disc technology developed between April 2004 and mid-2008 that can store up to several terabytes of data on an optical disc the same size as a CD, DVD or Blu-ray disc. It employs a technique known as collinear holography, whereby a green and red laser...
and Protein-coated disc
Protein-coated disc
Protein-Coated Disc is a theoretical optical disc technology currently being developed by Professor Venkatesan Renugopalakrishnan, formerly of Harvard Medical School and Florida International University. PCD would greatly increase storage over Holographic Versatile Disc optical disc systems...
formats.