Magnetic Disk Head Protrusion Control via Heater Resistance Ratio

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Solution Overview

Problem

In magnetic disk devices, the protrusion amount of write heads is often inaccurately specified by applying the protrusion sensitivity of read heads without measurement, leading to potential errors in the actual protrusion amount.

Innovation Solution

A magnetic disk device with a controller that adjusts the power supplied to heaters based on the ratio of electrical resistance values of the first and second heaters, allowing precise control of the flying height of both write and read heads, thereby accurately specifying their protrusion amounts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the protrusion sensitivity of read heads is applied directly to write heads without measurement, then the specification process is simplified, but the accuracy of protrusion amount specification deteriorates

Engineering Contradiction:

Improvespecification processVSAvoidprotrusion amount

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the measured protrusion amount of the read head is used to calculate and adjust the protrusion amount of the write head. The controller measures the read head's protrusion, calculates the write head's protrusion based on this measurement and the ratio between heaters' electric resistance values, and then adjusts the write head's protrusion accordingly. This feedback loop ensures accurate specification while maintaining process efficiency.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent uses the read head's measured protrusion amount as an intermediary to determine the write head's protrusion amount. Instead of directly measuring the write head (which would be complex), the system measures the read head first, then uses this intermediate measurement combined with the heater resistance ratio to calculate the write head's protrusion. This intermediary approach simplifies the overall measurement process while maintaining accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the protrusion amount of write heads is specified without measurement, then the manufacturing complexity is reduced, but the reliability of data recording deteriorates

Engineering Contradiction:

Improvemeasurement systemVSAvoiddata recording

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system uses feedback from the read head's measured protrusion to ensure reliable write head positioning. By continuously monitoring the read head's position and using this information to adjust the write head's protrusion based on the heater resistance ratio, the system ensures accurate and reliable data recording without requiring direct measurement of the write head.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The read head serves the dual purpose of both reading data and providing measurement information for write head positioning. The read head's measured protrusion amount is used to self-adjust the write head's position, eliminating the need for a separate measurement system for the write head while ensuring reliable data recording.

Inventive Principle:

Principle #25Self-service

3Ease of operation

If different powers are supplied to heaters without considering resistance ratios, then the control process is simplified, but the manufacturing precision of flying height adjustment deteriorates

Engineering Contradiction:

Improvepower controlVSAvoidflying height

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent changes the power supply parameters based on the electric resistance values of the heaters. The controller calculates the ratio between the first heater's resistance and the second heater's resistance, then adjusts the power supplied to each heater accordingly. This parameter adjustment ensures that both the write head and read head achieve their target protrusion amounts with high precision, maintaining ease of operation while improving manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

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 approach improves the accuracy in controlling the protrusion amount of write heads and enhances the reliability and performance of magnetic disk devices by minimizing write errors and optimizing data recording and reading processes.

Implementation Method 1

a first heater which adjusts a flying height of the write head

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a second heater which adjusts a flying height of the read head

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS12027189B2Magnetic disk device

Publication Date: 2024.07.02 KK TOSHIBA

AI summary

According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head including a write head which writes data to the magnetic disk, a read head which reads data from the magnetic disk, a first heater which adjusts a flying height of the write head, a second heater which adjusts a flying height of the read head and a controller which controls powers supplied to the first heater and the second heat, and controls a power value of the power supplied to the first heater according to a ratio between an electric resistance value of the first heater and an electric resistance value of the second heater.