Servo Control Processor Initial Frequency Offset for Disk Lock Clock
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Solution Overview
Problem
Conventional disk drives experience significant delays in initiating servo control and read/write operations due to the slow convergence of the disk lock clock control signal after transitioning from back EMF mode to servo control mode, leading to inaccurate head positioning and degraded data quality.
Innovation Solution
A novel frequency offset initializer is introduced in the servo control processor, which applies an initial frequency offset signal proportional to the spindle speed error, allowing the disk lock clock control system to converge more rapidly and enabling prompt initiation of servo control and read/write operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional feedback closed-loop control is used to initiate servo control, then the system is stable and reliable, but the convergence speed is slow causing significant delays in starting read/write operations
Solution Approach 1:
The patent applies preliminary action by initializing the frequency offset with an estimate derived from spindle speed error measurements taken during the transition from back EMF mode to servo control mode. This preliminary initialization occurs before the feedback closed-loop control begins operating, providing a head start that significantly accelerates convergence speed and eliminates startup delays without compromising the stability provided by the subsequent feedback control.
2Measurement precision
If the system waits for feedback closed-loop control to converge, then accurate head positioning is achieved, but read/write operations are delayed significantly
Solution Approach 1:
The patent performs preliminary initialization of the frequency offset using spindle speed error data obtained during mode transition, before servo control officially begins. This preliminary action provides an accurate initial estimate that enables the feedback closed-loop control to converge rapidly, thereby achieving both accurate head positioning and fast initiation of read/write operations without the significant delays characteristic of conventional systems.
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 solution enables disk drives to start servo control and read/write operations substantially faster, reducing initial closed-loop timing errors and ensuring accurate head positioning without the need for delays, thus improving data quality and performance.
Implementation Method 1
the frequency offset initializer applies an initial frequency offset control signal proportional to the spindle speed error, as the initial output of the servo control processor and feeding back into the input of the feedback closed-loop control system
Data Source
AI summary
Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position heads proximate to a recording medium of the disks; a spindle motor configured for rotating the one or more disks; and one or more processing devices comprising a servo control processor. The servo control processor is configured to receive a spindle speed error signal indicative of an error in a rotational speed of the spindle motor. The servo control processor is further configured to output an initial frequency offset signal, wherein the initial frequency offset signal is proportional to the spindle speed error signal.