Disk Drive Head Flying Height Control via Barometric Sensor

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Solution Overview

Problem

Existing disk drives face challenges in maintaining a stable dynamic flying height of the head due to inaccuracies in barometric pressure sensing, leading to potential head-disk contact and data read/write failures when the sensed pressure is higher than the actual value, resulting in excessive power supply to the adjusting element and an abnormally low dynamic flying height.

Innovation Solution

A disk drive system that includes a barometric pressure sensor, a calculation module to determine the required power for the adjusting element, a failure detection module to predict abnormal dynamic flying height, and an unload controller to prevent head-disk contact by unloading the head when sensor failure is detected, ensuring the dynamic flying height is maintained at a target value.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the power supplied to the adjusting element is controlled based on barometric pressure sensor output, then the dynamic flying height can be maintained at target value under normal conditions, but if the sensor fails or outputs incorrect values, the dynamic flying height becomes abnormal and head-disk contact may occur

Engineering Contradiction:

Improvedynamic flying height maintenanceVSAvoidhead-disk contact risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary detection of barometric pressure sensor status before using its output to control the adjusting element. By detecting sensor failures or abnormal readings in advance, the system prevents incorrect power supply to the adjusting element that would cause abnormal dynamic flying height and potential head-disk contact.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback control by continuously monitoring the barometric pressure sensor output and adjusting the power supplied to the adjusting element accordingly. Additionally, feedback mechanisms detect sensor failures and abnormal conditions, allowing the system to switch to alternative control modes or alert operators, thereby maintaining reliable dynamic flying height control.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If the barometric pressure detected by the sensor is higher than the actual value, then the calculated power supplied to the adjusting element becomes excessive, but this leads to abnormally low dynamic flying height and potential head-disk contact

Engineering Contradiction:

Improvebarometric pressure detection accuracyVSAvoiddynamic flying height stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The system performs preliminary verification of barometric pressure sensor readings before using them to calculate power for the adjusting element. Detection mechanisms identify sensor failures or readings that deviate from expected ranges, preventing incorrect power supply that would cause abnormally low dynamic flying height.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system applies partial correction to the barometric pressure sensor output by comparing it with reference values or alternative measurement methods. When sensor readings are suspected to be inaccurate, the system adjusts or limits the power supplied to the adjusting element to prevent excessive correction that would cause abnormally low dynamic flying height.

Inventive Principle:

Principle #16Partial or excessive action

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 system effectively maintains the dynamic flying height at a target value by accurately calculating the power supply to the adjusting element and preventing head-disk contact, thereby ensuring reliable data storage and preventing damage to the disk.

Implementation Method 1

a barometric pressure sensor, a calculation module configured to calculate the power to supply to the adjusting element from a barometric pressure detected by the barometric pressure sensor

Methodology Applied

Scientific EffectBarometric pressure sensing:

Implementation Method 2

The thermal actuator, for example, has its slider deformed through thermal expansion. Used as a heat source (adjusting element) that achieves the thermal expansion is a heater (resistive heating element). The heater is arranged at that part of the slider which lies near the head. In the thermal actuator, the power supplied to the heater is controlled, varying the thermal expansion of the slider (head).

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

The piezoelectric actuator has a slider, a suspension and a piezoelectric element. The suspension supports the slider. The piezoelectric element is arranged on the slider (or on the suspension). A voltage is applied to the piezoelectric element, adjusting the deformation of the slider.

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS7706098B2Disk drive in which the dynamic flying height of head is adjusted

Publication Date: 2010.04.27 KK TOSHIBA

AI summary

According to one embodiment, an adjusting element adjusts a dynamic flying height of a head lying over a disk in accordance with the power supplied to it. A calculation module calculates the power to supply to the adjusting element, from a barometric pressure detected by a barometric pressure sensor. A failure detection module detects failure of the barometric pressure sensor. An unload controller predicts an abnormal dynamic flying height of the head from the failure detected and then instructs the unloading of the head away from the disk.