Thermal Fly-Height Actuator Preheating Method
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Solution Overview
Problem
Conventional thermal fly-height actuators in magnetic recording disk drives experience higher error rates and risk of head-disk contact during initial data sector writes due to suboptimal fly-height and potential head crashes when the heater is activated during seeks.
Innovation Solution
A controller with a thermal fly-height actuator that deactivates the heater during seeks of a certain length and pre-heats the write head using a higher power read heater power value before writing, ensuring optimal head-disk spacing throughout the data sectors by applying the appropriate write heater power value once writing commences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the heater is activated during seeks to maintain optimal fly-height, then head-disk spacing is optimized, but the risk of head-disk contact and head crashes increases
Solution Approach 1:
The heater is pre-activated during the seek operation to warm up the write head before the actual write operation begins. This preliminary heating action ensures that when writing commences, the write head is already at the appropriate temperature to generate the necessary protrusion for optimal fly-height, eliminating the need to activate the heater during the write operation itself.
2Reliability
If the heater is deactivated during seeks to minimize head-disk contact risk, then head crash risk is reduced, but the write head lacks protrusion during initial data sector writes resulting in higher error rates
Solution Approach 1:
The heater is pre-activated during the seek operation to warm up the write head before the actual write operation begins. This preliminary heating action ensures that when writing commences, the write head is already at the appropriate temperature to generate the necessary protrusion for optimal fly-height, eliminating the need to activate the heater during the write operation itself.
3Manufacturing precision
If conventional thermal fly-height control is applied during writing, then head-disk spacing is controlled, but the first few data sectors have higher error rates due to lack of write head protrusion at ambient temperature
Solution Approach 1:
The heater is pre-activated during the seek operation to warm up the write head before the actual write operation begins. This preliminary heating action ensures that when writing commences, the write head is already at the appropriate temperature to generate the necessary protrusion for optimal fly-height, eliminating the need to activate the heater during the write operation itself.
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 method reduces error rates and minimizes the risk of head-disk contact by maintaining uniform fly-height and optimal head-disk spacing during writing, preventing initial sector write errors and potential disk failures.
Implementation Method 1
When current is applied to the heater the heater expands and causes the head to expand and thus move closer to the disk surface
Implementation Method 2
the write head experiences protrusion during a write operation as a result of heat from the write coil
Data Source
AI summary
A disk drive has a resistive heater located near the read/write head as a thermal fly-height actuator and uses an improved method for operating the fly-height actuator. As part of the method, the heater may be deactivated during a seek to minimize the risk of head-disk contacts. When a write command is received, a level of heater power is applied to pre-heat the write head prior to writing the initial data sectors. This pre-heating heater power level may be higher than the power level used for writing. Then when writing commences, the lower power level is applied to the heater so the write head has the optimal head-disk spacing during the writing of all the data sectors, including the initial data sectors. Even though the heater may be deactivated during the seek the controller can initiate pre-heating during the last portion of the seek before the write head has reached the target track.