High suction air bearing with pressure release

Details High suction air bearing with pressure release High suction air bearing with pressure release

1998-12-04

2002-09-03

Hudspeth, David (Department: 2652)

Dynamic magnetic information storage or retrieval

Fluid bearing head support

Disk record

C360S235400

Reexamination Certificate

active

06445541

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the field of mass storage devices. More particularly, this invention relates to a slider for use in a disk drive which includes a ramp for loading and unloading a transducing head to and from the disk.
BACKGROUND OF THE INVENTION
Computer systems have many different places where data can be stored. One common place for storing massive amounts of data in a computer system is on a disk drive. The most basic parts of a disk drive are a disk that is rotated, an actuator that moves a transducer to various locations over the disk, and electrical circuitry that is used to write and read data to and from the disk. The disk drive also includes circuitry for encoding data so that it can be successfully retrieved and written to the disk surface. A microprocessor controls most of the operations of the disk drive as well as passing the data back to the requesting computer and taking data from a requesting computer for storing to the disk.
The transducer is typically housed within a small ceramic block. The small ceramic block is passed over the disk in a transducing relationship with the disk. The transducer can be used to read information representing data from the disk or write information representing data to the disk. When the disk is operating, the disk is usually spinning at relatively high RPM. These days common rotational speeds are 7200 RPM. Some rotational speeds are as high as 10,000 RPM. Higher rotational speeds are contemplated for the future. These high rotational speeds place the small ceramic block in high air speeds. The small ceramic block, also referred to as a slider, is usually aerodynamically designed so that it flies over the disk. The best performance of the disk drive results when the ceramic block is flown as closely to the surface of the disk as possible. Today's small ceramic block or slider is designed to fly on a very thin layer of gas or air. In operation, the distance between the small ceramic block and the disk is very small. Currently “fly” heights are about 0.5-1.0 microinches. In some disk drives, the ceramic block does not fly on a cushion of air but rather passes through a layer of lubricant on the disk.
Information representative of data is stored on the surface of the memory disk. Disk drive systems read and write information stored on tracks on memory disks. Transducers, in the form of read/write heads, located on both sides of the memory disk, read and write information on the memory disks when the transducers are accurately positioned over one of the designated tracks on the surface of the memory disk. The transducer is also said to be moved to a target track. As the memory disk spins and the read/write head is accurately positioned above a target track, the read/write head can store data onto a track by writing information representative of data onto the memory disk. Similarly, reading data on a memory disk is accomplished by positioning the read/write head above a target track and reading the stored material on the memory disk. To write on or read from different tracks, the read/write head is moved radially across the tracks to a selected target track. The data is divided or grouped together on the tracks. In some disk drives, the tracks are a multiplicity of concentric circular tracks. In other disk drives, a continuous spiral is one track on one side of a disk drive. Servo feedback information is used to accurately locate the transducer. The actuator assembly is moved to the required position and held very accurately during a read or write operation using the servo information.
Disk drives have actuator assemblies which are used to position the slider and transducer at desired positions with respect to the disk. The slider is attached to the arm of the actuator assembly. A cantilevered spring, known as a load spring, is typically attached to the actuator arm of a disk drive. The slider is attached to the other end of the load spring. A flexure is attached to the load spring and to the slider. The flexure allows the slider to pitch and roll so that the slider can accommodate various differences in tolerance and remain in close proximity to the disk. The slider has an air bearing surface (“ABS”) which includes rails and a cavity between the rails. The air bearing surface is that portion of the slider that is nearest the disk as the disk drive is operating. When the disk rotates, air is dragged between the rails and the disk surface causing pressure, which forces the head away from the disk. At the same time, the air rushing past the depression in the air bearing surface produces a negative pressure area at the depression. The negative pressure or suction counteracts the pressure produced at the rails. The different forces produced counteract and ultimately fly over the surface of the disk at a particular fly height. The fly height is the thickness of the air lubrication film or the distance between the disk surface and the head. This film eliminates the friction and resulting wear that would occur if the transducing head and disk were in mechanical contact during disk rotation.
A constant goal of disk drive manufacturers is to increase the amount of information representing data that can be stored in a disk drive. One known way to increase data density is to lower the flying height of the slider. One way to lower the fly height is to use sliders having air bearing designs with larger areas which produce negative pressure. These designs are known as high suction air bearings. High suction bearings are very desirable since there is less variance in fly height when using a high suction bearing. The high suction air bearing sliders also have a relatively flat profile which means that the fly heights do not vary much when the slider is positioned at different radial positions. Overall, the high suction air bearing sliders have less altitude sensitivity.
Use of a high suction air bearing slider does have some drawbacks. One of the problems associated with high suction air bearing sliders is that when used in a disk drive where the slider and transducer are being loaded onto and unloaded off of the disk, the high suction force causes the air bearing surface to be subjected to an impulse loading which causes an excitation at the gimbal dimple and also may result in contact between the head and disk during unloading. The high suction force is not overcome until the load beam and arm are relatively far off the disk. As a result, the flexure is stretched out beyond its normal orientation. When the suction force is finally overcome, the slider is attached on the end of the flexure. This situation is like having a door spring attached to a door and pulling it well beyond the normal open position and then letting it go. The slider, like the door, will approach the gimbal dimple with too much force. The force of the stretched out flexure is much the same as the force associated with the door spring.
As a result, there is a need for a slider that will produce a high negative pressure while in transducing relation with respect to the disk. There is also a need for a slider which will release the high suction force early during the unloading process. Overcoming this problem will allow the use of high suction force air bearing sliders to be used on smooth disks without the problem of the slider either slapping the gimbal dimple or the slider exciting the gimbal dimple.
SUMMARY OF THE INVENTION
A disk drive system includes a base, a disk stack rotatably attached to the base, and an actuator assembly movably attached to the base. A ramp assembly includes a set of ramps for loading and unloading the sliders and transducing elements carried by the sliders to and from the disks in the disk stack. The ramp assembly is attached to the base. An actuator assembly is movably attached to the base of the disk drive. The actuator assembly includes one or more arms. A load spring is attached to the arm of the actuator. In some instances two load springs are attached to the arm of the actuator. A slider is attached to

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