Piezoelectric Head Gimbal Assembly for High Track Density Positioning
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Solution Overview
Problem
The existing head gimbal assemblies in hard disk drives face limitations in positioning accuracy due to the constraints of voice coil motor-driven actuators, particularly as tracks per inch increase, necessitating improved precision and stroke in the positioning of head-sliders over magnetic disks.
Innovation Solution
Incorporation of a piezoelectric element with a transmission wiring part, cross-connector, and adhesive fixing part to enhance the positioning accuracy and stroke of the head-slider, allowing for precise movement and protection against electrical connection damage, utilizing a two-stage actuator with voltage-controlled extension and contraction to finely position the head-slider.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voice coil motor-driven actuator is used, then the head-slider can be positioned over magnetic disks, but the positioning accuracy is limited as tracks per inch increase
Solution Approach 1:
The actuator system is segmented into two independent stages: a voice coil motor for coarse positioning and a piezoelectric element for fine positioning. This segmentation allows each stage to optimize for its specific function, with the piezoelectric element providing the necessary precision for high TPI disks while the VCM handles larger movements.
Solution Approach 2:
A piezoelectric element is introduced as an intermediary component between the VCM and the head-slider assembly. This intermediary provides the fine-adjustment capability needed to achieve high positioning accuracy, bridging the gap between the coarse VCM positioning and the precision requirements of high TPI tracks.
2Measurement precision
If piezoelectric element is added to enhance positioning accuracy, then positioning precision improves, but device complexity increases
Solution Approach 1:
The piezoelectric element is merged with the existing VCM actuator structure to form an integrated two-stage actuator system. The piezoelectric element is positioned to work in conjunction with the VCM, sharing common structural elements and control systems, which reduces the overall complexity increase despite adding functionality.
Solution Approach 2:
The piezoelectric element serves multiple functions: fine positioning adjustment, compensation for VCM positioning errors, and potential vibration damping. This multi-functionality justifies the added complexity by providing several benefits from a single component addition.
3Reliability
If piezoelectric element is mounted on transmission wiring part, then electrical connections are protected, but manufacturing complexity increases
Solution Approach 1:
The piezoelectric element is pre-mounted and electrically connected to the transmission wiring part before final assembly of the actuator system. This preliminary action ensures that electrical connections are established and protected early in the manufacturing process, preventing damage during subsequent assembly steps and reducing the need for complex post-assembly electrical work.
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
The solution enables improved positioning accuracy and increased stroke of the head-slider, preventing damage to electrical connections and allowing for superior control and reliability in positioning the head-slider over magnetic disks, thereby addressing the limitations of voice coil motor-driven actuators.
Implementation Method 1
a piezoelectric element which comprises; an upper surface, a first side surface, a second side surface, a lower surface, a first electrode, a second electrode, and a gap between the first and second electrodes on the lower surface, the piezoelectric element moving the stage by extension or contraction thereof according to a voltage applied to the first and second electrodes
Data Source
AI summary
A head gimbal assembly having a stage fixed to a head-slider. A piezoelectric element which comprises; an upper surface, a first side surface, a second side surface, a lower surface, a first electrode, a second electrode, and a gap between the first and second electrodes on the lower surface, the piezoelectric element moving the stage by extension or contraction thereof according to a voltage applied to the first and second electrodes. A transmission wiring part which has a connection pad for the piezoelectric element. A cross-connector for physically and electrically cross-connecting the first electrode and the connection pad. An adhesive fixing part which is formed from an insulating adhesive and adhesively fixes the lower surface of the piezoelectric element to the transmission wiring part, between an end of the second electrode at the gap and the cross-connector.