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Electronic Imaging & Signal Processing

PATENTS: Through thick or thin – New approaches for high-capacity optical storage

This month's featured patent review by analysts from Nerac.
17 October 2006, SPIE Newsroom. DOI: 10.1117/2.200610.0001
In keeping with the Dorothy Parker maxim that "You can never be too rich or too thin", DVDs are getting richer and thinner. Richer, of course, meaning greater storage capacity.
In the constant effort to carry more data on less material, some companies and groups are working on developing much lighter and thinner optical storage disks.
Hitachi Maxell applied in Japan for two patents on their thin optical disk and associated equipments and methods (both titled "Recording and reproducing apparatus of thin optical disc") back in 2005, both on the same day, August 10th.  They filed in the US three months later, a single application (20060101482/US-A1), in November.  Their Japanese patents were granted this June. A patent in the US could be granted as soon as May 2007 (18 months normal filing process time).  The disks are supposed to deliver terabyte storage ("One to One", June, p.10, or "CIO Tech Informer", Oct.4).
The abstract for the US application, which comprises both JP patents, reads as follows:
"In an apparatus for recording and reproducing a thin optical disk by using the same optical system as that of a CD, a DVD or the like, the invention provides a technique which can stably rotate the thin optical disk at a high speed. The structure can be made such that a turbulence of an airflow is not generated even if the thin optical disk on a turn table is rotated at a high speed, by employing a transparent turn table and arranging a recording and reproducing head or the like in an opposite side to a thin optical disk mounting surface of the turn table."
The higher capacity is achieved by using multiple thin disks. The thin disks are made compatible with existing systems by being paired with an acrylic disk that both adjusts the optical properties of the disk for reading in an ordinary system, and provides physical support. High density writing is managed cheaply again by using an acrylic disk to provide support, and adjust the optical properties to enable the use of a low-cost laser diode for writing. Hitachi Maxell is targeting large commercial storage systems, where this technology would provide a dramatic reduction in space requirements.
Hitachi Maxell is not the only company with super-thin disk technology in the patent process. Three authors, who are prolific in journal and conference publication, S. Murata, Y. Aman, and N. Onagi, of Ricoh Co. Ltd., of Kanagawa, Japan, also filed US applications on both ultra-thin flexible disks, and manufacturing methods (20040154035/US-A1 in January, and 20040228260/US-A1 in June 2004). Their system uses an air bearing to stabilize their flexible disk. Their patents have not yet been granted.
Older patents exist for similar concepts, all aiming at thinner, lighter, higher-capacity-for-less-floor-space devices.  The difference seems to be that Hitachi Maxell has targeted an application that is not highly dependent on maintaining the look and feel of common systems. In a commercial storage facility, an entire new wing of storage equipment could be populated with HM's high-density storage - and be scaled down to a mini-wing.
Another -- and more conventional -- approach to the constant challenge of fitting more information storage into less space is shown in Matsushita Electric Industrial Co., Ltd.'s new US patent 7,116,631, "Optical information recording medium manfacturing method therefor, manufacturing apparatus therefor, and optical information recording and reproducing apparatus" which was just filed October 3 of this year.
Its abstract reads: "In an optical information recording medium having at least two information layer, guide grooves for tracking or sample pits or information pits corresponding to information signals are formed on a surface of a first substrate. A first information layer formed by a thin film for reflecting a portion of a light beam made incident on the first substrate and permitting penetration of a portion of the light beam is formed on a surface of the first substrate. Guide grooves for tracking or information pits corresponding to information signals are formed on a surface of a second substrate. A second information layer having a reflectance higher than that of the first information layer is formed on a surface of the second substrate. Between the first information layer and the second information layer, there is formed a transparent separation layer for positioning the first information layer and the second information layer to be spaced a predetermined distance apart from each other."
Matsushita's high-capacity disk concept involves layered information, on the same sort of sturdy disk construction that the industry is familiar with. Perhaps this is a safer approach for this market? But perhaps it does not allow improvement on the same scale as the more novel thin disk concept.
Margaret Fiore is a Nerac Patent Analyst. Nerac's Intellectual Property Solutions provide a practical understanding of the IP landscape, helping organizations to make informed decisions about R&D planning and business strategy development. Nerac analysts work with clients in the following critical areas:
  • Patentability and Invalidity
  • Patent Portfolio Analysis
  • Commercialization Strategy
  • White Space Analysis