Disc drive head slider with recessed landing pads

Details Disc drive head slider with recessed landing pads Disc drive head slider with recessed landing pads

1998-06-19

2004-02-03

Klimowicz, William (Department: 2652)

Dynamic magnetic information storage or retrieval

Fluid bearing head support

Disk record

C360S237100, C360S236500, C360S236600, C360S235900

Reexamination Certificate

active

06687088

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to the field of hard disc drive data storage devices, and more particularly, but not by way of limitation, to an improved slider body configuration for supporting a data transducer in cooperative relationship with a rotating data storage disc.
BACKGROUND OF THE INVENTION
Disc drives of the type known as “Winchester” disc drives or hard disc drives are well known in the industry. Such disc drives record digital data on a plurality of circular, concentric data tracks on the surfaces of one or more rigid discs. The discs are typically mounted for rotation on the hub of a brushless DC spindle motor. In disc drives of the current generation, the spindle motor rotates the discs at speeds of up to 10,000 RPM.
Data are recorded to and retrieved from the discs by an array of vertically aligned read/write head assemblies, or heads, which are controllably moved from track to track by an actuator assembly. The read/write head assemblies typically consist of an electromagnetic transducer carried on an air bearing slider. This slider acts in a cooperative hydrodynamic relationship with a thin layer of air dragged along by the spinning discs to fly the head assembly in a closely spaced relationship to the disc surface. In order to maintain the proper flying relationship between the head assemblies and the discs, the head assemblies are attached to and supported by head suspensions or flexures.
The actuator assembly used to move the heads from track to track has assumed many forms historically, with most disc drives of the current generation incorporating an actuator of the type referred to as a rotary voice coil actuator. A typical rotary voice coil actuator consists of a pivot shaft fixedly attached to the disc drive housing base member closely adjacent the outer diameter of the discs. The pivot shaft is mounted such that its central axis is normal to the plane of rotation of the discs. An actuator housing is mounted to the pivot shaft by an arrangement of precision ball bearing assemblies, and supports a flat coil which is suspended in the magnetic field of an array of permanent magnets, which are fixedly mounted to the disc drive housing base member. On the side of the actuator housing opposite to the coil, the actuator housing also typically includes a plurality of vertically aligned, radially extending actuator head mounting arms, to which the head suspensions mentioned above are mounted. When controlled DC current is applied to the coil, a magnetic field is formed surrounding the coil which interacts with the magnetic field of the permanent magnets to rotate the actuator housing, with the attached head suspensions and head assemblies, in accordance with the well-known Lorentz relationship. As the actuator housing rotates, the heads are moved radially across the data tracks along an arcuate path.
When power to rotate the discs is lost; the hydrodynamic relationship between the heads and the discs rapidly deteriorates and the heads are no longer capable of flying above the disc surface in the intended manner. Similarly, a loss of power to the disc drive also terminates the ability of the disc drive to control the actuator which moves the heads across the discs. It is therefore common in the industry to move the actuator to a “park” location when a loss of power is detected and to latch the actuator at this park position until power is restored to the disc drive. This is done to prevent relative movement between the heads and discs when the heads and discs are in contact, since such relative motion could easily result in fatal damage to the heads, the discs or both.
While some disc drives of the current generation employ “parking ramps” located near the outer diameter of the discs to remove the heads from the discs and thus prevent head/disc contact during power-off conditions, the most common method of dealing with this situation is referred to as “contact start/stop”,in which a specially designated area of the disc surfaces, usually located near the inner diameter of the discs, is set aside as a parking zone to which the heads are automatically moved at the detection of a power loss. The parking zone contains no recorded data, and, once the discs have slowed sufficiently that the heads lose their flying ability, the heads are brought to rest in contact with the disc surfaces and locked in this position until the restoration of power.
One difficulty with the contact start/stop type of disc drive occurs when the disc drive is repowered and tries to reestablish the air bearing between the heads and discs, and involves the phenomenon typically referred to in the industry as “stiction”. Since the discs used in disc drives are typically coated with a lubricant to minimize damage to the heads or discs during incidental head/ disc contact, and since a small amount of water vapor within the disc drive housing is substantially unavoidable, a liquid miniscus forms between the head and disc when they are in contact. Because the air bearing surfaces of the heads are precision lapped to be as flat as possible, this liquid miniscus acts to bind the heads to the disc surfaces, creating stiction. This stiction must be overcome by the spindle motor in order to accelerate the discs and begin flying of the heads.
Many solutions to the problem of stiction have been proposed, including the intentional texturing of the disc surface at the parking zone, to minimize the contact area between the heads and discs and thus reduce the size and force of the liquid miniscus. It has also been suggested to include landing pads which protrude toward the disc above the air bearing surface, to prevent the full area of the air bearing surfaces from contacting the disc surface, thus also reducing the stiction phenomenon, but such designs have typically been undesireable compromises between stiction reduction and unwanted increased separation of the data transducer from the disc. Such increased separation of the transducer from the disc lowers the available data resolution, and thus limits the data density which can be provided, leading to lowered capacity of the disc drive.
It would be desireable, therefore, to provide an apparatus that reduces stiction while optimizing the flying relationship between the data transducer and the disc.
SUMMARY OF THE INVENTION
The present invention is a slider body configuration, or slider, for carrying a data transducer in cooperative relationship with a rotating data storage disc. The slider includes a plurality of landing pads which serve to minimize the contact area between the slider and the discs when the heads are parked in contact with the discs, and the landing pads project from surfaces which are farther removed from the disc surface than the air bearing surfaces, thus minimizing the size and strength of any liquid miniscus formed between the slider and the disc when the slider and disc are in contact. By recessing the bases of the landing pads from the air bearing surfaces, the effect of the landing pads on the separation between the data transducer and the discs is minimized.
It is an object of the invention to provide a slider body configuration for mounting and carrying a data transducer in cooperative relationship with a rotating data storage disc.
It is another object of the invention to provide a slider body configuration that reduces the liquid miniscus between the slider and the disc when the slider and the disc are in contact.
It is another object of the invention to provide a slider body configuration that optimizes the spatial relationship between the data transducer and the disc.
It is another object of the invention to provide a slider body configuration that is simple and ecomical to manufacture.


REFERENCES:
patent: 4605977 (1986-08-01), Matthews
patent: 5034828 (1991-07-01), Ananth et al.
patent: 5267104 (1993-11-01), Albrecht et al.
patent: 5285337 (1994-02-01), Best et al.
patent: 5508861 (1996-04-01), Ananth et al.
patent: 4-341984 (1992-11-01), None

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