Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
2000-10-11
2004-03-23
Sniezek, Andrew L. (Department: 2697)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S235800, C360S236300, C360S236200, C360S236100
Reexamination Certificate
active
06710964
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to disc storage systems for storing information. More specifically, the present invention relates to padded sliders for use in ramp load and contact start/stop disc storage systems.
BACKGROUND OF THE INVENTION
Disc drives of the “Winchester” and optical types are well known in the industry. Such drives use rigid discs, which are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor, which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.g. air) bearing disc head sliders. The sliders carry transducers, which write information to and read information from the disc surfaces.
An actuator mechanism moves the sliders from track-to-track across the surfaces of the discs under control of electronic circuitry. The actuator mechanism includes an actuator arm and a suspension. The slider is coupled to the suspension assembly through a gimbaled attachment. The suspension provides a load force to the slider which forces the slider toward the disc surface. The slider includes a bearing surface, which faces the disc surface. As the disc rotates, the disc drags air under the slider and along the bearing surface in a direction approximately parallel to the tangential velocity of the disc. As the air passes beneath the bearing surface, air compression along the air flow path causes the air pressure between the disc and the bearing surface to increase, which creates a hydrodynamic lifting force that counteracts the load force and causes the slider to lift and “fly” in close proximity to the disc surface to enable the transducing head carried by the slider to perform read or write operations. The gimbaled attachment to the suspension allows the slider to pitch and roll while following the topography of the disc.
One measurement of disc drive performance is the loading performance of the disc drive. This generally relates to the time that is required for the disc drive to become “ready” or be capable of reading data from, or writing data to, the disc surface. One contributing factor to the loading performance of disc drives is the time that is required to load the slider above the disc surface. This is typically the time that is required for the disc to accelerate its rotation to a full operating speed. The full operating speed of the disc drive is a rotational velocity, at which the tangential velocity of the disc generally exceeds a minimum operating velocity for the slider at all radial positions along the disc where the slider will operate. The minimum operating velocity relates to the minimum tangential velocity of the disc at which the air bearing, that is required for the slider to fly, can form.
Demands for increased disc storage capacity have led to lower slider fly heights and smoother disc surfaces. Unfortunately, the development of ultra-low flying sliders is impaired by a phenomenon called stiction. Stiction is caused by static friction and viscous sheer forces, which cause the slider to stick to the disc surface after periods of none-use. Stiction can be overcome by the spindle motor provided that sufficient torque to overcome the stiction can be produced. However, the head and/or the disc can be damaged when the slider is freed from the disc surface.
Contact Start/Stop (CSS) disc drives operate with the slider in contact with the disc surface during start and stop operations when there is insufficient disc rotational speed to maintain the bearing. To alleviate stiction problems, some CSS disc drives provide a dedicated landing zone near the inner diameter of the disc by generating, in a controlled fashion, asperities or texture, on the disc surface. The texture acts to reduce the area of contact at the slider-disc interface. Although this solution reduces the likelihood of disc drive failure due to stiction, there is also a reduction in the area of the disc surface that can be used for data storage. Furthermore, the presence of these asperities on the media surface can enhance the chance of slider-media contact during operation and thereby sets the limit to the true attainment of ultra-low flying sliders.
Another type of disc drive is a ramp load or ramp load/unload disc drive. Ramp load disc drives eliminate the need of having to “park” the slider on the disc surface by using a ramp, from which the slider is loaded above the disc surface and unloaded from the disc surface. The ramp is generally adapted to hold the slider by the suspension and is typically located adjacent the outer diameter of the disc. Prior to shutting the drive down, the actuator mechanism unloads the flying slider from the disc surface by rotating the suspension on to the ramp. Once the slider is unloaded, the disc is allowed to slow its rotational velocity from the full operating speed and the drive can be shut down. At start up, the actuator mechanism delays loading the slider on to the disc surface until the rotational velocity of the disc reaches the full operating speed.
The ramp load type of disc drive is one solution to the problems associated with CSS drives, such as the need for a dedicated landing zone and the slow loading times. The need for a dedicated landing zone is eliminated in the ramp load disc drive, since it is not necessary for the slider to land on the disc surface. As a result, ramp load disc drives are capable of maximizing the effective data storage are of the disc. However, ramp load disc drives are not problem free.
One problem that is encountered in ramp load disc drives is that the slider can occasionally contact the disc surface during ramp load operations when the required air bearing beneath the slider is not fully formed. This contact is undesirable due to the possibility of damaging the disc surface and/or the slider, which could result in data loss and disc failure. One possible solution to this is to provide a dedicated load zone at the outer diameter of the disc surface where no data is written. Unfortunately, this solution results in a decrease of the effective data storage area of the drive.
Ramp load disc drives can also encounter problems with stiction. This can occur, for example, when power to the disc drive is interrupted or when the suspension is knocked off the ramp. As a result, the potential exists for ramp load disc drives to fail due to stiction.
There exists a need for improving the loading performance of ramp load disc drives while reducing the likelihood of disc drive failure due to stiction and damage caused by contact between a slider and a disc surface during ramp load operations.
SUMMARY OF THE INVENTION
The present invention is directed to a ramp load disc drive storage system having improved loading performance and a reduced likelihood of failure due to stiction and damage caused by contact between a slider and a disc surface during ramp load operations. One aspect of the present invention is directed to a method of operating a ramp load disc drive where a slider is supported relative to a surface of a disc within the disc drive. The slider includes a contact pad on a disc-facing surface. A rotational velocity of the disc is accelerated toward a full operating speed and the slider is loaded onto the disc surface from a ramp that is positioned adjacent an edge of the disc prior to the disc reaching the full operating speed.
Another aspect of the present invention is directed toward a disc drive storage system that includes a disc, a slider, a suspension, and a ramp. The disc has a disc surface and is rotatable at an operating rotational velocity. The slider includes a leading slider edge, a trailing slider edge, and first and second rails positioned therebetween and disposed about a central recess. The first and second rails include contact pads. A third rail is disposed along the trailing slider edge, between the first and second rails, and supports a transducer. The first and second rails form first and second bearing surfaces, and the third rail
Boutaghou Zine-Eddine
Hipwell Mary C.
Patel Dilip C.
Pottebaum Ken L.
Rao Mukund C.
Olson Jason
Seagate Technology LLC
Westman Champlin & Kelly
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