Moving Magnet Actuator for Tape Head Tracking
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Solution Overview
Problem
Magnetic tape data storage systems face limitations in data density due to the reliance on track width and separation for reliable read/write operations, leading to waste of tape surface and potential misalignment issues with narrow heads, and existing track following servo systems struggle with rapid lateral shifts causing tracking errors.
Innovation Solution
A balanced actuator system for the tape head using a magnet and a return path structure, where the magnet self-centers and generates a magnetic field to pivot the lever and head, allowing for improved dynamic response and reduced constraint force, eliminating the need for springs or flexures and potentially reducing damping requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If track width and separation are increased to ensure reliable read/write operations, then read/write reliability is improved, but data density is reduced due to waste of magnetic tape surface
Solution Approach 1:
The patent replaces the traditional mechanical positioning system (static head with mechanical movement) with a magnetic field-based actuation system. The moving magnet actuator uses magnetic attraction and repulsion forces to position the read/write head, eliminating the need for mechanical friction and wear-prone components. This substitution enables more precise and reliable head positioning, allowing narrower track widths and separations while maintaining read/write reliability, thus increasing data density.
2Quantity of substance
If track width and read/write head width are narrowed to increase data capacity, then data density is improved, but misalignment between head and track occurs leading to read/write failures
Solution Approach 1:
The patent replaces mechanical positioning mechanisms with a moving magnet actuator that uses magnetic fields for head positioning. This electromagnetic actuation system provides finer control resolution and more precise positioning, enabling the head to accurately follow narrow tracks without misalignment. The magnetic actuation system can achieve sub-micron positioning precision, ensuring reliable read/write operations even with tightly spaced tracks.
Solution Approach 2:
The patent introduces a dynamic actuation system that can rapidly adjust head position in response to track variations. The moving magnet actuator provides high-bandwidth control, allowing the head to dynamically follow track wander and maintain alignment during tape movement. This dynamic positioning capability ensures continuous reliable operation with narrow tracks that would be impossible with static mechanical positioning.
3Reliability
If a compound actuator with coarse and fine actuators is used for track following, then tracking capability is improved, but system complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the coarse actuator from the compound actuator system, relying solely on the fine moving magnet actuator for both coarse and fine positioning. The moving magnet actuator is designed with a limited range of travel but high bandwidth, and is positioned within the tape path to provide sufficient positioning authority without requiring a separate coarse positioning mechanism. This simplification reduces system complexity while maintaining full tracking capability.
Solution Approach 2:
The patent makes the fine moving magnet actuator perform both coarse and fine positioning functions that traditionally required separate actuators. By positioning the actuator within the tape path and designing it with appropriate travel range and bandwidth, a single actuator handles all positioning needs, eliminating the need for dual-actuator complexity.
4Manufacturing precision
If springs or flexures are used to center the read/write head, then head positioning is achieved, but manufacturing complexity and damping requirements increase
Solution Approach 1:
The patent replaces mechanical centering mechanisms (springs, flexures) with a magnetic field-based centering system. The moving magnet actuator uses magnetic attraction to a centered pole piece to automatically center the read/write head assembly. This magnetic centering eliminates the need for precision-machined spring mounts or flexure assemblies, significantly simplifying manufacturing while achieving precise head centering. The magnetic force provides both centering and restoring forces without mechanical contact.
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 solution enhances the dynamic response and tracking accuracy of the tape head, enabling higher data density on magnetic tape while being resistant to shock and vibration, and simplifies the manufacturing process by eliminating the need for springs or damping fluids.
Implementation Method 1
a magnet self-centers, in the absence of a coil generated magnetic field, in the middle of a gap of a magnetic return path structure
Implementation Method 2
conducting current through a coil to generate a magnetic field which is conducted by the return path structure to interact with the magnetic field of the magnet
Implementation Method 3
the mass of the read/write head and one side of the lever may be balanced by the mass of the magnet and the other side of the lever
Data Source
AI summary
In one embodiment, a tape read/write head supported by a lever is biased in a first position, using magnetic attraction between a magnet supported by the lever, and a return path structure of magnetically permeable material. In the illustrated embodiment, the magnet centers itself, in the absence of a coil generated magnetic field, in the middle of a gap of the magnetic return path structure. In one aspect, the mass of the read/write head and one side of the lever may be balanced by the mass of the magnet and the other side of the lever. The lever and hence the tape read/write head carried by the lever, may be pivoted by conducting current through a coil to generate a magnetic field which is conducted by the return path structure to interact with the magnetic field of the magnet. As a consequence, the lever pivots on a pivot axis as a function of the magnitude and direction of the current through the coil. The face of the magnet may be divided into portions of opposite magnetic polarity to facilitate a relatively pure torque to be developed substantially without a net force. Other embodiments are described and claimed.