Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
1998-06-29
2001-02-06
Tran, Thang V. (Department: 2753)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S047360, C369S044320, C360S078090
Reexamination Certificate
active
06185171
ABSTRACT:
The present invention relates generally to control systems involving data storage apparatuses, and more specifically relates to a control system which accommodates vibrations resulting from rotating a data storage medium in a data storage apparatus.
BACKGROUND
Data storage apparatuses typically provide that some type of data storage medium is rotated as data is read from or written to the data storage medium. For many different reasons, the rotation of the data storage medium usually results in at least some amount of vibration. For example, due to manufacturing tolerances, the data storage medium typically is not perfectly planar. As a result, the disc storage medium may wobble when it is rotated. Of course, the wobble becomes greater with higher speeds of rotation, and increased vibrations are produced. As a consequence of the wobble and vibrations, data may not be able to be retrieved from or written to the data storage medium, or worse, the data storage medium and/or the data storage apparatus may become damaged as a result of rotating the data storage medium.
Vibrations resulting from rotating a data storage medium in a data storage apparatus are particularly prevalent when a data storage apparatus is used to rotate several different data storage media where each data storage medium is removable from the data storage apparatus and is relatively heavy. One example of the foregoing is where the data storage apparatus is used with several different removable data storage media. In this case, due to the different manufacturing tolerances in the industry, the vibrations which will result from rotating a given data storage medium are extremely difficult, if not impossible, to predict.
Additionally, some removable data storage media, such as CD-ROMS, are relatively heavy which causes a substantial amount of inertia when the disc is rotated.
Several other factors may contribute to the vibrations which result from rotating a data storage medium. For example, typically, data storage media, such as a CD-ROM, include a label and/or ink thereon which provides visible indicia relating to the contents of the data storage medium, the source of the data storage medium, etc. Along with manufacturing tolerances, the label and/or ink distribution may provide another source of imbalance when the data storage medium is rotated, and may increase the vibrations resulting from the rotation thereof.
Still more sources of vibrations resulting from rotating a data storage medium, such as CD-ROM, are manufacturing tolerances of the spindle and chuck assembly which chucks, or retains, the data storage medium, and the precision with which the chuck actually engages the data storage medium before and during rotation.
Augmenting the unpredictability of the vibrations resulting from rotating a given data storage medium is the manner in which some data storage devices operate. Some typical data storage devices operate in a Constant Linear Velocity (CLV) mode where the angular velocity of the data storage medium is varied to provide a substantially constant linear velocity of the medium under the data (data read and/or data write) head as the head is moved radially across the disc. Generally, present data storage devices provide a two-and-a-half time speed difference from the slowest angular velocity when the data head is at the outermost portion of the medium to the fastest angular velocity when the data head is at the innermost portion of the medium. Such speed changes inevitably produce different vibration characteristics.
While data storage devices have actually evolved to operate in a modified or zoned Constant Angular Velocity (CAV) mode, such drives span a two to three times difference between the minimum and maximum spindle speeds. Therefore, vibrations are still an issue.
While data storage devices have become faster and faster in recent years, vibrations resulting from rotating a data storage medium have limited the speed at which the medium can be rotated and have limited the rate at which data can be reliably read from or written to the medium. In fact, the overall reliability of a data storage device generally degrades with faster rates of rotation. The emergence of, for example, DVD-ROM drives with a faster data rate for a given comparable spindle rate also requires minimal vibration in order to improve read and writeability. In fact, with the rotation of any data storage medium comes the necessity to counteract the vibrations which result from the rotation in order to read or write data as quickly as possible.
OBJECTS AND SUMMARY
It is an object of the present invention to provide a control system which suitably accommodates the vibrations resulting from rotating a data storage medium.
It is a further object of the present invention to provide a control system which counter-acts the vibrations associated with rotating a data storage medium.
It is a further object of the present invention to provide a control system which can adapt to different data storage media and speeds of rotation.
It is a further object of the present invention to provide a control system which allows data to be reliably read from or written to a data storage medium which is rotating at a relatively high spindle rotation rate including, possibly, a spindle rotation rate which is higher than the present state of the art.
In accordance with these and other objects, the present invention provides a control system for attempting to accommodate the vibrations resulting from rotating a data storage medium in a data storage apparatus. The control system includes a neural network which utilizes detected vibrations resulting from the rotation of data storage media to learn the characteristics of the rotational imbalance of the rotating data storage media and subsequently controls rotation of a data storage medium and/or movement of the data head based on the characteristics learned.
One aspect of the present invention provides a balance control system for attempting to balance a rotating data storage medium. The balance control system includes at least one balancing actuator contactable with the rotating data storage medium, and a data head associatable with the rotating data storage medium for reading data from and/or writing data to the rotating data storage medium, where the data head is capable of detecting data tracks on the rotating data storage medium. The system also includes control circuitry in communication with the data head for counting the data tracks on the rotating data storage medium detected, and includes a processor in communication with the control circuitry and the one or more balancing actuators. The processor receives from the control circuitry information related to the data tracks detected by the data head and derives balancing actuator direction information. The processor communicates the balancing actuator direction information to the one or more balancing actuators thereby altering the vibration of the data storage medium. Preferably, a plurality of orthogonal linear actuators contact the rotating data storage medium so that the rotation of the data storage medium can be altered precisely in two, or preferably three, dimensions. Also, preferably the data head is floatable in response to rotational imbalance of the rotating data storage medium, where the data head detects data tracks on the rotating data storage medium while the data head is floating.
In addition to, or as an alternative to, the above, a balance control system in accordance with the present invention may include a detector associated with the data head for detecting a light beam directed to a rotating data storage medium. The balance control system further includes a processor in communication with the detector and one or more balancing actuators. The processor receives from the detector information related to the light beam on the data storage medium and derives balancing actuator direction information therefrom, and the processor communicates the balancing actuator direction information to the one or more balancing actuators thereby
Bassett Stephen J.
Winchell Michael A.
LSI Logic Corporation
Tran Thang V.
LandOfFree
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