Flexible Head Gimbal Assembly Stroke Sensitivity
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Solution Overview
Problem
Existing head gimbal assemblies in hard disk drives face a challenge in achieving high yaw frequency while maintaining sufficient stroke sensitivity without increasing the length of PZT actuators, which would negatively impact the gimbal structure and yaw frequency.
Innovation Solution
The head gimbal assembly incorporates a gimbal structure with a base portion, tongue, and neck portion, where the base portion and tongue have openings adjacent to the neck portion, connected by flexible struts, and the tongue includes cutouts to enhance in-plane flexibility, thereby improving stroke actuation without compromising yaw frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the length of PZT actuators is increased to improve stroke sensitivity, then stroke sensitivity is improved, but yaw frequency is reduced
Solution Approach 1:
The gimbal structure is divided into separate functional components: a base portion for mounting PZT actuators, a tongue for slider mounting, and connecting struts for flexible connection. This segmentation allows the PZT actuators to be positioned optimally for stroke sensitivity while the tongue and connecting struts provide the necessary flexibility for yaw movement, resolving the contradiction between stroke sensitivity and yaw frequency
Solution Approach 2:
Flexible connecting struts act as intermediaries between the base portion and the tongue. These struts transmit the actuation force from the PZT actuators while allowing the tongue to rotate freely for yaw frequency operation. The struts mediate between the need for stroke sensitivity (from PZT actuators) and yaw frequency requirements, enabling both functions to coexist without compromising either
2Measurement precision
If the gimbal structure is made more flexible to improve stroke actuation, then stroke sensitivity is improved, but structural stability is reduced
Solution Approach 1:
Different portions of the gimbal structure have different flexibility characteristics tailored to their specific functions. The connecting struts are designed with specific flexibility to enable stroke actuation, while the base portion and tongue maintain sufficient rigidity for structural stability. This local differentiation of mechanical properties allows the structure to be stable where needed while flexible where required
Solution Approach 2:
The connecting struts are designed with specific geometric parameters (length, cross-section, material properties) that optimize the balance between flexibility and stability. By carefully selecting and adjusting these parameters, the struts provide enough flexibility for stroke actuation while maintaining structural stability during operation, resolving the contradiction between actuation performance and structural integrity
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 stroke sensitivity by allowing more flexible in-plane rotational movement of the tongue, while maintaining the high yaw frequency, thus improving the overall performance of the head gimbal assembly in hard disk drives.
Implementation Method 1
PZT actuators 20 mounted to the gimbal 14... PZT actuators 20... that rotate a portion of the gimbal assembly for fine positioning of the slider
Implementation Method 2
the base portion and tongue have openings adjacent to the neck portion, connected by flexible struts, and the tongue includes cutouts to enhance in-plane flexibility
Implementation Method 3
The pressure caused by air viscosity between the slider and the spinning disk causes the slider to hover over (in close proximity to) the surface of the disk
Data Source
AI summary
A head gimbal assembly includes a gimbal, a circuit, a slider, a first PCT actuator, and a second PZT actuator. The gimbal includes a base portion and a tongue that are connected by a neck portion, wherein the base portion includes a first opening located adjacent the neck portion such that the base portion is connected to the neck portion by a pair of first connecting struts, and the tongue includes a second opening located adjacent the neck portion such that the tongue is connected to the neck portion by a pair of second connecting struts. The circuit is mounted on the gimbal. The slider is mounted on the tongue, and electrically connected to the circuit. The first PZT actuator and the second PZT actuator are mounted to the head gimbal assembly and electrically connected to the circuit, for displacing the tongue relative to the base portion.