TDK Corp. exhibited a sample of a new media device called “ML-R” or Multi-Level-R, with a storage capacity equal to three CD-Rs, at the optical-technology exhibition “InterOpto2001” held July 16-July 19 at the Makuhari Messe convention center.
TDK announced its plan to commercialize the new media within fiscal 2001.
The technology underlying the ML-R was developed by Calimetrics Inc. of the United States, for achieving three times the storage capacity as well as a three-times faster data transfer rate than a CD-R media. The new technology introduces eight different sizes of recording marks and makes a reflection coefficient variable according to each size so as to store three bits in each mark.
Using this method, a disk with a diameter of 120mm can record 2GB of data. There is no need to prepare a different type of drives as well as optical and mechanical systems than those used for a current CD-R, but the ML-R does require an exclusive LSI microchip. This new media is downward compatible, and thus a drive unit for an ML-R disc can be used for recording into and replaying an ordinary CD-R/RW.
The recording media consists of coloring agents, common to current media, such as a cyanine pigment. As it features eight different sizes of recording mark areas, there are special arrangements set for laser power and radiation time. Differences in reflection coefficients can be detected according to the difference in size of recording mark areas.
Providing eight sizes of areas means any recording mark can present a signal expressed by three bits following its size. Consequently, the recording density per unit length is three times larger, and thus the new media ML-R can record 2GB of data over the same time as a current CD-R. Thus, when using a 12x drive in terms of rotation, data transfer by the ML-R disc is performed as if it is using a 36x unit.