Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2001-04-25
2003-06-17
Miller, Brian E. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
Reexamination Certificate
active
06580584
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to magnetic head assemblies for rotating disk drives, and particularly, to head assemblies having a leading edge step scheme for tuned air entrainment.
BACKGROUND OF THE INVENTION
Disk drives of the type that receive data storage media typically have a head assembly for communicating with the storage medium. The data storage cartridge may be of the type that is removable from the disk drive. The storage medium may be disk shaped, and if so, the data storage cartridge may be referred to as a disk cartridge. The head assembly may include a pair of sliders. Each slider is typically mounted on an actuator that is mounted within a disk drive. Additionally, each of the sliders may have a read/write sensor(s) for interfacing with a storage medium of a disk cartridge. The sliders are also commonly referred to as read/write heads.
Generally, the actuator on which the head assembly is mounted moves between a retracted position and an interfacing position. In the retracted position, the heads are disposed in a position that minimizes the likelihood of damage to the heads from either dynamic or static forces. When a disk cartridge has not been inserted into the disk drive, the actuator holds the heads in this retracted position. When a disk cartridge is inserted into the disk drive, the actuator moves the heads to the interfacing position. In the interfacing position, the actuator is in a position in which the heads can interface with the storage medium that has been inserted into the disk drive.
The storage medium with which the head assembly may interface may have a top surface and a bottom surface. Preferably, in the interacting position the storage medium is disposed between the sliders of the head assembly. One of the sliders may be disposed proximal to the top surface, and one of the sliders may be disposed proximal to the bottom surface. In operation, the storage medium of the disk cartridge is rotated between the sliders and an air bearing is created between the storage medium and each of the sliders. As the storage medium is rotated, the storage medium “rides” on this air bearing and the heads interface with the storage medium.
The design of head assemblies is significant because it affects the ability of the heads to interface with the storage medium of the disk drive. In particular, the ability of the heads to interface with the storage medium is a function of the spacing between the sliders and the storage medium. The spacing between the sliders and the media is important because it affects the ability of the disk drive to communicate with the media. Ordinarily, the sliders fly very low with respect to the media, and in some instances, such as with flexible media, a portion of the sliders may contact the media. As the distance between the media and the sliders increases, the signal degrades. With the development of higher density media, it is desired to develop sliders that have even lower fly heights than those previously developed.
For instance, one of the concerns when designing head assemblies is that the spacing between the read/write heads and the storage medium be relatively constant. If the spacing between the read/write heads and the storage medium is not relatively constant, this can cause a degradation in the ability of the heads to interface with the storage medium. The importance of maintaining the spacing between the storage medium and the heads relatively constant is even, more pronounced in disk cartridges that have storage mediums with a relatively high density.
In order to maintain an appropriate spacing between the read/write heads and the storage medium, the air bearing created between the slider and the storage medium should be relatively constant. At high speeds, the flexible storage medium tends to flutter and therefore the importance of maintaining the spacing between the read/write heads and the storage medium is even more pronounced at high speeds. In addition to being dependent on the speed of rotation of the storage medium, the air bearing is a function of the geometry of the head assemblies and the storage medium. Therefore, the geometry of these components is of particular importance.
Slider performance can be measured using several parameters. For example, one important parameter is the “fly height,” which is the distance between the magnetic transducer on the read-write head and the magnetic layer on the disk. Another important parameter is “roll,” which is the difference between the distance between the inside rail and the disk surface and the distance between the outside rail and the disk surface while the read-write head is flying over the disk. Another important parameter is “pitch,” which is the difference between the distance between the leading edge and the disk surface and the distance between the trailing edge and the disk surface while the read-write head is flying over the disk.
A class of conventional sliders are sliders which include a leading edge, a trailing edge, first and second side edges, first and second raised side rails positioned along first and second side edges, respectively, and leading edge tapers for facilitating a flow of air under the side rails during takeoff and for helping to maintain an air bearing under the slider as it flies over the surface of the disk. In this regard, reference is made to U.S. Pat. Nos. 5,831,791 and 5,949,614, both issued to Chhabra (U.S. Pat. No. 5,949,614 is a continuation of U.S. Pat. No. 5,831,791). These patents show and describe an Adjustable Negative Pressure Air Bearing (NPAB) Slider which provides means for controlling the slider characteristics including roll, pitch, fly height, and skew sensitivity. The NPAB slider controls the flying characteristics of the slider by providing a positive pressure, negative pressure, and transition regions whereby the shape of the regions determines the direction and amount of air flowing into the negative pressure region and thus the magnitude and distribution of negative pressure generated. One embodiment of the slider disclosed has side rails with tapered leading edges, and another embodiment includes side rails with leading edge steps.
For high capacity flexible magnetic recording technology, it is desired that there be contact between the flexible media and the part of the head where the sensor is located. The balance of the head should fly over the flexible media in order to maximize the amount of data that can be stored to and read from the surface of a disk.
In addition to affecting the performance of the head assembly, the spacing between the head assembly and the storage medium also affects the life of both the read/write heads and the storage medium. For instance, if the storage medium fluctuates, the storage medium and the heads may wear unevenly and their respective lives may be reduced. Furthermore, if the air bearing pressure is relatively high, the storage medium and the heads will wear at a faster rate. The amount of fluctuation of the storage medium is a function of a large number of variables, including, for example, the geometry of the head assembly and the storage medium, the cartridge shell, rotational velocity, the media mechanical properties (e.g., size, thickness, substrate material, etc.), and the like. Manufacturing imperfections in head assemblies and/or variations in drives and head assemblies due to large design tolerances have the potential to cause an imbalance of forces between the head assembly and the storage medium and subsequent fluctuations of the storage medium. Accordingly, it is important to design head assemblies, so that the manufacturing tolerances are relatively low and the likelihood of manufacturing imperfections is reduced.
In addition, although it is preferred to have leading edge tapers that are machined, modem manufacturing techniques for higher capacity heads/sensors only support heads that are etched, not machined. As a result, it is necessary to develop improved leading edge steps instead of ramps.
Therefore, a need exists for hea
Iomega Corporation
Miller Brian E.
Woodcock & Washburn LLP
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