Head lifter and method of operation

Details Head lifter and method of operation Head lifter and method of operation

1998-10-15

2003-03-18

Korzuch, William R. (Department: 2653)

Dynamic magnetic information storage or retrieval

Head mounting

For moving head into/out of transducing position

C360S294700

Reexamination Certificate

active

06535356

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
This invention relates in general to the field of mass storage devices, and more particularly to a head lifter and method of operation that may be used in a hard disk drive.
BACKGROUND OF THE INVENTION
Hard disk drives include a stack of magnetically coated platters that are used for storing information. The magnetically coated platters are mounted together in a stacked position through a spindle which may be referred to as a platter stack. The platter stack is typically rotated by a motor that is referred to as a spindle motor or a servo motor. A space is provided between each platter to allow a read/write head or slider to be positioned on each side of each platter so that information may be stored and retrieved. Information is stored on each side of each platter and is generally organized into sectors, tracks, zones, and cylinders.
Each of the read/write heads or sliders are mounted to one end of a dedicated suspension arm so that each of the read/write heads may be positioned as desired. The opposite end of each of the suspension arms are coupled together at a voice coil motor, also referred to as a head actuator, to form one unit or assembly that is positionable by the voice coil motor. Each of the suspension arms are provided in a fixed position relative to each other. The voice coil motor positions all the suspension arms together so that the active read/write head is properly positioned for reading or writing information. The read/write heads or sliders may move from an inner diameter to an outer diameter. This distance may be referred to as a data stroke.
When a hard disk drive is initially powered-up, the read/write heads must transition from a state of resting on the surface of the associated platter to a flying height position above the surface of the associated platter. When fully powered-up, the read/write heads are, in effect, riding on a cushion of air above the surface of the platters. In this state, the read/write heads may be referred to as “flying.”
Problems arise when a hard disk drive is initially powered-up. The cumulative friction between each of the plurality of read/write heads and their corresponding platter results in a cumulative friction that must be overcome before starting up the rotation of the platter stack. This may be referred to as a “sticking” problem. For example, many hard disk drives have as many as nine platters with two read/write heads per platter. Oftentimes, the read/write heads are positioned over data during start-up which potentially leads to the problem of damaged or destroyed data because of the friction between the read/write head and the surface of the platter during start-up. Read/write heads are generally provided as ultra-smooth heads such that the read/write heads and the platters almost fuse together after the platters stop spinning. This further increases the “sticking” problem.
Prior attempts at solving this high torque condition at start-up have focused on shaking or rapidly moving the voice coil motor to free the heads from this fused or high
20
. torque condition. In some cases, these attempts fail and the platters do not rotate or spin resulting in potential catastrophic damage to the spindle motor. This technique may result in the loss of data due to the shaking of the heads on the surface of the platters. Other attempts at solving this problem have focused on using ramps to position the read/write heads above the platters. This too has proven difficult and cumbersome to implement.
Once the read/write heads transition from being positioned on the surface of the platters to flying above the surface of the platters, a drag torque is created which increases with the rotational speed of the platters. This reduces the platter rotational speed. This is undesirable because hard disk drive data access time is related to the spindle speed. Thus, the drag torque reduces the spindle or platter speed and hence limits the overall hard disk driveability to retrieve data quickly.
SUMMARY OF THE INVENTION
From the foregoing it may be appreciated that a need has arisen for a head lifter and method of operation that solves the high torque and “sticking” problem that occurs at start-up and the drag torque problem that occurs when all of the read/write heads are flying and positioned slightly above the surface of the rotating platters. In accordance with the present invention, a head lifter and method of operation that may be used in a hard disk drive are provided which substantially eliminate the disadvantages and problems outlined above.
According to the present invention, a read/write head assembly is provided for use in a mass storage device such as a hard disk drive. The read/write head assembly is located on a suspension arm and includes a read/write head and a head lifter. The head lifter positions the read/write head in a first position and a second position.
The present invention provides numerous technical advantages. One technical advantage of the present invention includes the capability to start-up a mass storage device, such as a hard disk drive, with a lower starting torque by preventing the read/write heads from sticking to the platters. This significantly increases data reliability and reduces the chances for a catastrophic data or system failure. Another technical advantage of the present invention includes reduced drag torque when the read/write heads are positioned above the rotating platters. This allows for increased platter speeds, which is also referred to as increased spindle speeds, which provides the capability to retrieve data faster from hard disk drives and mass storage devices.
Yet another technical advantage of the present invention includes increased spindle speeds while using the same spindle motor power supply. This results in power savings that are especially important in portable applications such as laptop computers and notebook computers. Still yet another technical advantage of the present invention includes the capability to achieve increased spindle speeds at reduced overall costs as compared to other techniques. For example, other techniques to achieve increased spindle speeds focus on such things as expensive and exotic bearings to reduce spindle friction and the use of expensive spindle motor power supplies that operate at higher voltages than standard spindle motor power supplies. Other technical advantages are readily apparent to one skilled in the art from the following figures, description, and claims.


REFERENCES:
patent: 5717630 (1998-02-01), Koshikawa et al.

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