Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
1997-11-10
2001-08-07
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
C360S097020, C360S265900
Reexamination Certificate
active
06271996
ABSTRACT:
BACKGROUND
Technical Field
The present invention relates generally to suspensions for supporting read/write heads over recording media. In particular, the present invention is a head suspension having damping structures.
BACKGROUND OF THE INVENTION
Magnetic head suspensions are well known and commonly used with dynamic magnetic storage devices or drives with rigid disks. The head suspension is a component within the disk drive which positions a magnetic read/write head over the desired position on the storage media where information is to be retrieved or transferred. Head suspensions typically include a load beam supporting a flexure to which a head slider having read/write head is mounted. The head slider allows the read/write head to “fly” on an air bearing generated by the spinning magnetic disk. The flexure allows pitch and roll motion of the head slider and read/write head as they move over the data tracks of the magnetic disk. Head suspensions can also include an actuator arm to which the load beam is mounted and which is for attachment to a voice coil or other type of actuator.
With the advent of more powerful computers and the rapid growth in the personal computer market it has become increasingly more important to enable the user to access data from storage devices with increased speed and accuracy. Because of this need to reduce access times to enable rapid retrieval of data it has become increasingly important to reduce levels of vibration of components within the rigid disk drive. In relation to this, an important consideration in the design of head suspensions is resonance characteristics. Resonance vibrations of drive components can cause instability of the drive's servo system. It also may delay the transfer of data because the data cannot be confidently transferred until the amplitude of the vibration has substantially decayed.
Of particular importance are the first and second torsion resonance modes and lateral bending (or sway) resonance modes of vibrations. These resonance modes can result in lateral movement of the head slider at the end of the head suspension and are dependent on cross-sectional properties along the length of the load beam. Torsion modes sometimes produce a mode shape in which the tip of the resonating suspension moves in a circular fashion. However, since the head slider is maintained in a direction perpendicular to the plane of the disk surface by the stiffness of the load beam acting against the air bearing, lateral motion of the rotation is seen at the head slider. The sway mode is primarily lateral motion.
The use of dampers on head suspensions to decrease resonance vibrations is generally known and described in U.S. Pat. Ser. No. 5,187,625 issued to Blaeser et al. on Feb. 16, 1993 and U.S. Pat. Ser. No. 5,299,081 issued to Hatch et al. on Mar. 29, 1994.
Use of dampers in head suspension design and construction typically involves use of constraint layers to cover otherwise exposed surfaces of the damper. Constraint layers are often formed from stainless steel or other rigid material. Therefore, they can add weight to the head suspensions. Additional weight in the head suspension can adversely impact shock characteristics thereof. In particular, it can increase the amount of time for avibration caused by aphysical shock to the head suspension, which may simply be caused by stopping the head over data track, to decay to a point where information can be accessed from the disk. As such, increased mass can result in increased information access times.
Increased mass in the head suspension can also require more power for the voice coil actuator to move the head suspension over the spinning disk surface, particularly in multiple disk and multiple head drives. Increased power consumption is particularly problematic with drives used in battery operated systems such as laptop computers.
Accordingly, there is a continuing need for improved damping of head suspensions. In particular, addition of damper material to a head suspension should change as little as possible the properties of the load beam (e.g. gram loading, spring rate, shock performance, etc.) and should add as little weight as possible to the head suspension. Further, it is advantageous if the method of damping can be used on a variety of head suspension designs. Additionally, the damped suspension should be reliable and capable of being efficiently manufactured.
SUMMARY OF THE INVENTION
The present invention is an improved damper structure for a head suspension. The head suspension includes a load beam with a mounting region at a proximal end, a rigid region adjacent to a distal end, and a spring region between the mounting region and the rigid region. A flexure is located at the distal end of the load beam for supporting a read/write head. A damping region having a continuous surface is also formed on the head suspension. Damping material is located on the damping region and has at least one unconstrained surface. The damping material is for damping resonance vibrations of the head suspension.
In one embodiment, at least one reservoir is located in the damping region of the head suspension. The reservoir can be formed by walls of epoxy resin or it can be formed from the material of the head suspension itself by either stamping or partial etching. Damping material is dispensed into the reservoir to form a damper. The damping material is preferably visco-elastic material.
A method of fabricating the head suspension includes providing a load beam as described above and forming thereon a continuous damping region. Damping material is placed in the damping region such that one surface of the damping material remains unconstrained.
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Houk Galen D.
Zhou Haiming
Faegre & Benson LLP
Hutchinson Technology Incorporated
Renner Craig A.
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