Preamp Rotational Parameter Control via Serial Interface
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Solution Overview
Problem
Conventional serial communication methods for updating preamplifier parameters in magnetic recording devices are too slow and can interfere with read/write operations, making it difficult to adjust parameters within the short windows available between data and servo areas, leading to jitter issues.
Innovation Solution
Implementing preamp rotational parameter control using standard digital serial interface lines to generate a special signal pattern that allows for digital signal transfers during the read/write recovery gap, enabling updates to multiple parameters per disk revolution without requiring an external DAC for thermal fly-height control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional serial communication methods are used to update preamplifier parameters, then parameter updates can be performed, but the update speed is too slow and causes interference with read/write operations
Solution Approach 1:
The patent applies preliminary action by pre-configuring the preamplifier parameters during manufacturing or initialization, storing multiple parameter sets in the preamp memory. During operation, the appropriate parameter set is selected and activated without requiring slow serial updates, thus maintaining high update speed while avoiding interference with read/write operations.
Solution Approach 2:
The patent implements dynamics by enabling real-time parameter switching based on operational conditions. The system can dynamically select between different parameter sets stored in the preamp, allowing rapid parameter changes without serial communication overhead, thus improving update speed while maintaining reliability through interference-free operation.
2Productivity
If serial data is transmitted outside of gap areas, then parameter updates can be performed more frequently, but interference with read and write data causes jitter issues
Solution Approach 1:
The patent applies copying by creating duplicate parameter storage locations within the preamp memory. Multiple copies of parameter sets are stored locally, eliminating the need for repeated serial transmissions. This allows high update frequency through local selection while maintaining signal accuracy by avoiding transmission during critical read/write periods.
3Adaptability or versatility
If an external DAC is used for thermal fly-height control, then parameter adjustment capability is provided, but only one parameter can be adjusted and noise on the analog line causes error
Solution Approach 1:
The patent merges multiple parameter control functions into a single integrated digital interface. Instead of using a separate external DAC for fly-height control, the system combines TFC, Iw, OSA, and OSD parameter control through the same serial interface, allowing simultaneous adjustment of multiple parameters while maintaining precision through digital signaling without analog noise interference.
Solution Approach 2:
The patent replaces the external analog DAC system with an integrated digital control system. By substituting the analog signal path with digital parameter storage and selection within the preamp, the system eliminates analog line noise while maintaining full parameter adjustment capability, thus improving measurement precision without sacrificing adaptability.
4Productivity
If multiple parameters are updated within a single disk revolution, then operational efficiency is improved, but the time window for updates is extremely limited
Solution Approach 1:
The patent applies preliminary action by pre-storing multiple parameter sets in the preamp memory during manufacturing or initialization. This allows the system to rapidly switch between pre-configured parameter sets during operation without requiring time-consuming serial updates, thus achieving high operational efficiency within the limited time window of a single disk revolution.
Solution Approach 2:
The patent implements dynamics by enabling real-time parameter set selection based on operational conditions. The system can dynamically activate different parameter sets stored in memory, allowing multiple parameter updates per disk revolution through local memory access rather than serial communication, thus improving productivity while working within the constrained time window.
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 allows for rapid and interference-free updates of preamplifier parameters, including fly-height and write driver settings, within a single disk revolution, eliminating the need for external analog signal control and reducing jitter issues.
Implementation Method 1
The fly-height actuator can be a thermal actuator that includes heater located on the slider near the read/write head
Implementation Method 2
The fly-height controller includes circuitry for adjusting the current through heat element resistor
Data Source
AI summary
Disk drives with preamp rotational parameter control (RPC) using standard digital serial interface lines to the preamp are described. The standard serial interface lines are used to generate a special signal pattern that does not follow the serial communication protocol. The special signal pattern is used to implement RPC when doing so will not interference with other signals, preferably in the read/write recovery gap between the data and the servo field in a standard track format. A value of a selected preamp parameter can be incremented or decremented by one LSB during the read/write gap time in each servo sector as the disk rotates. Embodiments of the invention allow fly-height and write driver parameters to be varied inside of a single disk revolution. Embodiments are described that include two or four parameters in the set, which allows for multiple updates of each parameter per revolution of the disk.