Reduction of electrostatic charge build-up in storage medium

Details Reduction of electrostatic charge build-up in storage medium Reduction of electrostatic charge build-up in storage medium

1999-05-14

2001-09-18

Psitos, Aristotelis M. (Department: 2651)

Dynamic information storage or retrieval

Storage medium structure

Specified center hole or locating structure

C369S289100, C369S291100

Reexamination Certificate

active

06292459

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to data storage, and more particularly, to structures of storage media and systems.
BACKGROUND
A disk in a disk drive for data storage may build up electrostatic charge on its surfaces. Such electrostatic charge can be generated by several mechanisms including rubbing with surrounding components in the disk drive (e.g., the disk cartridge or shuttle), human or robotic handling of the disk cartridge that causes transfer and accumulation of electrostatic charge to the disk, and tribological charging of the disk by contacting the read-write head.
In many optical disk drives, a disk embossed with grooves and pits for tracking and servo and a cartridge for holding the disk are usually made of non-conductive materials. For example, these materials such as plastic, dielectric materials, or other non-conductive materials can be prone to build-up of static charge and may be charged up to a high static voltage. In a near-field optical disk drive, where the optical head is spaced from the disk during operation by less than one wavelength (e.g., a small fraction of one wavelength), static charge on the disk surface can accumulate to a static voltage on the order of several kilo volts.
SUMMARY
Methods and disk designs to reduce accumulation of electrostatic charge in a disk are provided to dissipate electrostatic charge out of the disk. An electrically-conducting path is implemented to transfer the electrostatic charge to a reference ground.
A data storage device of one embodiment includes a substrate having at least a substrate surface, a coupling unit (e.g., a disk hub) engaged to the substrate, a conducting layer formed on the substrate and the coupling unit, a storage layer formed on the conducting layer, and at least one dielectric layer formed over the storage layer. The coupling unit has a bottom surface and a top surface. The bottom surface is in contact with the substrate surface so that the top surface is elevated from the substrate surface. The conducting layer covers a portion of the substrate surface and a portion of the top surface of the coupling unit to form an electrically conducting path from the substrate to the top surface of the coupling unit. The storage layer and the dielectric layer are formed over at least a portion of the substrate.
Another embodiment of the data storage device has a disk which includes a substrate and a disk hub formed on a center of one surface of the substrate, and a spindle motor having a conducting spindle engaged to the disk hub to hold and rotate the disk. The disk includes a contiguous conducting layer disposed in part on the surface of the substrate and in part on the disk hub to form an electrically-conducting path from the substrate to the disk hub, a storage layer formed on the conducting layer, and at least one dielectric layer formed over the storage layer. The conducting spindle is in contact with said conducting layer to receive static charge accumulated on the disk.
A disk may include conducting layers on both sides of the disk substrate. The two conducting layers may be electrically coupled to each other so both can be grounded through a contact with the conducting spindle. One way to achieve this is to deposit the metal layers without an outer diameter mask so that the metal layer contiguously wraps around the outer edge to cover both sides of the substrate.
These and other aspects and associated advantages will become more apparent in light of the detailed description, the accompanying drawings, and the appended claims.


REFERENCES:
patent: 4836890 (1989-06-01), Murata et al.
patent: 4871404 (1989-10-01), Murata et al.
patent: 5226033 (1993-07-01), Takahashi
patent: 5289456 (1994-02-01), Takahashi
patent: 5369632 (1994-11-01), Takahashi
patent: 5453884 (1995-09-01), Takahashi

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