The present invention relates to the field of laser servowriting of optical servo tracks on data storage media. More particularly, the present invention relates to apparatus and methods of stabilizing flexible media during laser servowriting of optical servo tracks on the media.
Laser servowriting of data storage media involves processing the surface of the media to provide discontinuities, such as grooves or pits, in the surface that can be used as a reference to allow for optical positioning of the read/write mechanisms used to store and/or retrieve information on the media. The process typically involves ablating material or otherwise modifying the surface of the media in a manner that allows for precise control over the position of the read/write mechanisms during use of the media. By relying on servowritten tracks as a reference to optically locate the read/write mechanisms, storage density of data on the media can be increased by providing more precise location of the read/write mechanisms. One example of a data storage product using servowritten tracks to increase storage density includes the LS-120 SuperDisk(trademark) marketed by Imation Corp., St. Paul, Minn.
Typical laser servowriting equipment includes a rotating platter on which the media is placed to perform the servowriting operation. Those servowriting systems suffer from variations in the distance between the platter and the laser optics as the optics move radially relative to the platter during servowriting. Those variations are typically of a magnitude sufficient to place the media surface outside of the depth of focus of the laser energy, leading to differences in the depth and/or width of the servo tracks which can affect optical contrast. Those differences in servo track depth, width, and/or optical contrast can reduce the accuracy of positioning the read/write mechanisms.
As a result, improved methods and apparatus of stabilizing the vertical position of flexible media in laser servowriting systems are needed to allow for reliable production of higher density data storage products.
The present invention provides methods and apparatus for stabilizing data storage media during laser servowriting of optical servo tracks on the media. The apparatus includes a spindle for rotating the media during servowriting, a fixed media platform, and a media support for stabilizing the vertical position of the media during servowriting.
The present invention can reduce one source of error in the distance between the laser optics and the media surface in known servowriting systems, i.e., the entrapment of dust and debris between the rotating platform and media. The entrapment of dust and debris is reduced by rotating the media above a fixed media platform and provides increased control over the distance between the laser servowriting optics and the media. That control results in more precise location and formation (i.e., width and/or depth) of the optical servo tracks, and, therefore, increased data storage density on the media.
Another advantage is that by providing a laser servowriting apparatus that includes a fixed or stationary media platter, cycle time of the servowriter, i.e., the time required to process a disk, can be reduced because of the reduced mass-moment of intertia of the system. That reduction causes a corresponding decrease in the time required to accelerate the media to the desired speed with the same size motor, thereby decreasing cycle time.
In one aspect, the present invention provides an apparatus for stabilizing data storage media during laser servowriting of optical servo tracks on the media, the apparatus including a spindle for rotating the media during servowriting; a fixed media platform; and a media support for stabilizing the vertical position of the media during servowriting. The media support may include channels or channels and a vacuum slot formed therein to enhance performance of the apparatus.
In another aspect, the present invention provides an apparatus for stabilizing data storage media during laser servowriting of optical servo tracks on the media, the apparatus including a spindle for rotating the media during servowriting; a fixed media platform; a media support for stabilizing the vertical position of the media during servowriting, the media support comprising a plurality of channels aligned generally tangential to the spindle and an upper surface having a crown located above the upper surface of the media platform.
In another aspect, the present invention provides a method of stabilizing data storage media during laser servowriting of optical servo tracks on the media, the method including steps of placing the media on a spindle; stabilizing the vertical position of the media by rotating the media above a fixed media platform and a media support; and laser servowriting optical servo tracks on the media. In some methods, the media support can include channels formed therein and, in further variations, the methods can include drawing a vacuum through the channels.
These and other features and advantages of the invention are described more completely below.