Piezoelectric Microactuator on Disk Drive Flexure Tongue
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Solution Overview
Problem
Current microactuator designs for hard disk drives face challenges in providing adequate bandwidth and stroke while minimizing dynamics and unwanted vibrations, and often require complex structures that increase manufacturing costs and complexity.
Innovation Solution
A microactuator design is implemented where a piezoelectric element is distally located on the laminated flexure's tongue, with a structural layer configuration that includes outrigger beams and head mounting plates to reduce unwanted coupling and enhance vertical stiffness, allowing for pure rotary motion and improved bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a piezoelectric microactuator is affixed to the mounting plate or load beam, then the microactuator is positioned proximally to provide structural support, but the bandwidth and stroke are reduced due to the dynamics introduced by the intermediate structure of the suspension assembly
Solution Approach 1:
The patent relocates the piezoelectric microactuator from proximal positions (mounting plate or load beam) to the distal end of the flexure tongue, changing the spatial dimension of actuator placement. This dimensional shift eliminates the intermediate structure dynamics between the actuator and read head, thereby maximizing bandwidth and stroke while maintaining structural integrity through the flexible printed circuit board integration
2Speed
If the microactuator is disposed distally on the flexure tongue, then the bandwidth is improved, but the stroke is reduced due to the lever arm effect
Solution Approach 1:
The patent changes the physical parameters of the flexure tongue structure by incorporating a flexible printed circuit board with conductive traces that can accommodate distal actuator placement. The flexible circuit board's mechanical properties are optimized to provide sufficient stroke transmission while maintaining electrical connectivity, thereby resolving the trade-off between bandwidth improvement and stroke reduction
3Reliability
If complex structures are used to accommodate the microactuator, then the actuation performance is improved, but the manufacturing cost and complexity increase
Solution Approach 1:
The flexible printed circuit board serves multiple functions simultaneously: it provides the structural substrate for distal microactuator placement, transmits mechanical motion from the actuator to the read head, and maintains electrical connectivity for signal transmission. This multi-functionality eliminates the need for separate structural components, thereby simplifying manufacturing while maintaining actuation performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the bandwidth and stroke of the microactuator while reducing unwanted vibrations and manufacturing complexity, providing a more efficient and cost-effective solution for fine actuation in hard disk drives.
Implementation Method 1
a piezoelectric element is distally located on the laminated flexure's tongue
Data Source
AI summary
A disk drive head gimbal assembly includes a laminated flexure with a tongue having an actuated portion that rotates about an axis of rotation by expansion of an adhered piezoelectric element. A non-actuated portion of the tongue adjoins and forms a bridge between two outrigger beams, with a dimple contact location that is in contact with a dimple of the load beam and through which the axis of rotation passes. The piezoelectric element has an anchored end that is adhered to the non-actuated portion of the tongue, and an opposing actuated end adhered to the actuated portion. The actuated portion of the tongue includes first and second head mounting plates that are each adhered to the read head. Each of the head mounting plates is connected to the non-actuated portion of the tongue by an elongated compliant member that is oriented radially with respect to the dimple contact location.