Single-Actuator Disk Drive Suspension for Low Arm Sway
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Solution Overview
Problem
Conventional suspension assemblies with paired PZT actuators for disk drives face complexity and excite unwanted arm sway modes, making precise head positioning challenging as track densities increase.
Innovation Solution
A disk drive suspension assembly with a single actuator formed of a crystal material that expands and contracts along orthogonal axes in response to bias voltages, allowing for simplified manufacturing and reduced arm sway modes by rotating the load beam about a center within the load beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pair of PZT actuators is used for fine positioning, then positioning resolution is improved, but device complexity increases
Solution Approach 1:
The patent combines the functions of two separate PZT actuators into a single PZT actuator with two independent electrodes. This single actuator can expand or contract in two orthogonal directions by applying voltages to different electrode pairs, thereby reducing device complexity while maintaining the fine positioning capability that previously required two actuators
2Measurement precision
If a pair of PZT actuators is used for fine positioning, then positioning resolution is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges two separate actuator mounting operations into a single actuator installation. The single PZT actuator with integrated dual-electrode configuration simplifies the mounting process on the base plate, reduces the number of alignment steps, and simplifies wiring connections, thereby improving ease of manufacture while achieving the same positioning resolution
3Ease of operation
If conventional PZT actuators are driven to rotate the load beam, then positioning control is achieved, but arm sway modes are excited
Solution Approach 1:
The patent changes the actuation parameters by using a single PZT actuator with selective electrode activation instead of driving two actuators simultaneously. By applying voltage to specific electrode pairs in a controlled sequence, the actuator can rotate the load beam in desired directions while minimizing the excitation of arm sway modes through optimized voltage application timing and magnitude
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 single actuator design simplifies manufacturing and significantly reduces arm sway modes, improving servo control performance and precise head positioning without the need for additional filters.
Implementation Method 1
the single actuator is formed of a crystal material that expands along a first axis of the single actuator and contracts along a second axis of the single actuator orthogonal to the first axis in response to a first bias voltage, and expands along the second axis and contracts along the first axis in response to a second bias voltage that is opposite in polarity to the first bias voltage
Data Source
AI summary
A suspension assembly includes a load beam, a base plate connected to the load beam, and a single actuator disposed in an opening of the base plate. The single actuator is formed of a crystal material that expands along a first axis and contracts along a second orthogonal axis, and expands along the second axis and contracts along the first axis in response to respective first and second bias voltages. The single actuator is configured to flex the base plate when expanding along the first axis to rotate the load beam in a first rotational direction about a center of rotation located along the load beam, and flex the base plate when expanding along the second axis to rotate the load beam in a second, opposite rotational direction about the center of rotation.