Magnetic Disk Heater Voltage Control for Levitation Stability
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Solution Overview
Problem
Magnetic disk devices face a tradeoff between stable write performance and preheat time, where prolonged preheat times improve stability but degrade write performance, and applying voltage during high seek velocities risks magnetic head contact with the disk due to levitation variations.
Innovation Solution
A magnetic disk device with a control section that applies a first voltage to the heater during seek operations and transitions to a second, higher voltage before starting write operations, managing heater power to maintain optimal levitation and prevent contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If preheat time is prolonged to stabilize write operation, then write stability is improved, but write performance is deteriorated
Solution Approach 1:
The heater voltage is applied in advance during the seek operation to warm the element section before write operation begins. This preliminary heating action ensures that when writing starts, the element section is already at the appropriate temperature, stabilizing write operation without requiring extended preheat time that would delay write performance.
2Loss of time
If voltage is applied to heater during high seek velocity, then preheat can start earlier, but levitation amount becomes insufficient and magnetic head contact risk increases
Solution Approach 1:
The heater voltage application is dynamically controlled based on seek velocity. During high-speed seek operation, voltage is applied to start preheating early, but the voltage level is adjusted according to the changing seek velocity. As seek velocity decreases near the target position, the voltage is increased to ensure adequate levitation amount, preventing magnetic head contact while maintaining early preheat initiation.
Solution Approach 2:
The heater voltage parameter is changed according to seek velocity conditions. During high-speed seek, a lower voltage is applied to minimize levitation variation, while near the target position where seek velocity is lower, the voltage is increased to ensure sufficient levitation amount. This parameter adjustment resolves the contradiction between early preheat start and contact prevention.
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 stabilizes levitation and improves write conditions at the start of writing, suppressing variations in levitation amounts and preventing magnetic head contact with the disk, thus enhancing write performance without extending preheat times.
Implementation Method 1
applying a voltage to the heater before write is started... applying a voltage to the heater element to thereby warm the element section
Implementation Method 2
the magnetic head is temporarily brought into contact with the recording surface of the magnetic disk, and is thereafter levitated by a predetermined amount
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, a heater a control section. When making the magnetic head carry out the seek operation from the first position to the second position, the control section starts application of a first voltage to the heater while the seek operation is carried out and, after application of the first voltage, makes the voltage to be applied to the heater a second voltage greater than the first voltage before the magnetic head is positioned to the second position and write of data is started by the magnetic head.