Thermally-Assisted Magnetic Recording Head Return Path Segmentation

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Solution Overview

Problem

Thermally-assisted magnetic recording heads face challenges in achieving excellent write characteristics in high frequency bands due to high coil resistance, which is exacerbated by the need to prevent the medium facing surface from colliding with the recording medium, leading to deterioration in write characteristics and increased error rates.

Innovation Solution

The thermally-assisted magnetic recording head is designed with a return path section that includes columnar portions and a coil wound around a smaller third columnar portion, allowing the first and second columnar portions to be brought closer to the medium facing surface, reducing the total length of the coil and minimizing resistance, while maintaining a configuration where the core and return path section intersect without contacting each other.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the coil length is reduced to lower resistance, then write characteristics in high frequency bands are improved, but the medium facing surface may collide with the recording medium

Engineering Contradiction:

Improvewrite characteristicsVSAvoidcollision between medium facing surface and recording medium

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The return path section is divided into multiple columnar portions (first, second, and third columnar portions) positioned at different locations. This segmentation allows the coil to be wound around a specific portion (third columnar portion) that is closer to the medium facing surface, reducing coil length and resistance while maintaining safe clearance from the recording medium through strategic positioning of segmented structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a conventional linear return path configuration to a three-dimensional arrangement of columnar portions distributed in space. By positioning columnar portions at different locations and winding the coil around a specific spatial arrangement, the design achieves shorter effective coil length while maintaining the necessary separation from the recording medium through spatial optimization.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Loss of energy

If the return path section is positioned closer to the medium facing surface to reduce coil length, then coil resistance decreases, but the core and return path section may contact each other

Engineering Contradiction:

Improvecoil resistanceVSAvoidcontact between core and return path section

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The return path section is segmented into multiple columnar portions positioned at different locations relative to the core. The third columnar portion, which the coil is wound around, is positioned closer to the medium facing surface to reduce coil length, while the first and second columnar portions maintain appropriate spacing from the core to prevent contact. This segmentation enables differential positioning to simultaneously achieve low resistance and prevent harmful contact.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The columnar portions serve as intermediary structures that mediate between the core and the coil winding. By introducing these intermediate columnar elements at specific positions, the design achieves close proximity to the medium facing surface for reduced coil length while the columnar structure itself acts as a spacer to prevent direct contact between the core and return path section.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration enhances write characteristics in high frequency bands and reduces coil resistance, preventing collisions with the recording medium and improving overall write performance.

Implementation Method 1

light propagating through the waveguide is totally reflected at the outer surface of the waveguide to thereby generate evanescent light

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a plasmon generator, which is a piece of metal that generates near-field light from plasmons excited by irradiation with laser light

Methodology Applied

Scientific EffectSurface plasmon excitation:

Data Source

PatentUS8498183B1Thermally-assisted magnetic recording head having a waveguide and a return path section

Publication Date: 2013.07.30 HEADWAY TECHNOLOGIES INC

AI summary

A thermally-assisted magnetic recording head includes a coil, a main pole, a return path section, a waveguide, and a plasmon generator. The waveguide includes a core and a cladding. The return path section includes: first and second columnar portions located on opposite sides of the core in the track width direction; a coupling portion coupling the first and second columnar portions to each other; and a third columnar portion connected to the coupling portion. The third columnar portion is smaller than the coupling portion in width in the track width direction. The coil includes a winding portion wound around the third columnar portion.