Multi-Actuator Servo Interface Circuitry for Parallel Self-Servo Writing

Solution Overview

Problem

The existing self-servo writing process in hard disk drives (HDDs) is inefficient and costly due to the lack of onboard hardware support for parallel self-servo writing with multiple read/write heads, leading to prolonged manufacturing times and increased costs.

Innovation Solution

A circuit and method for parallel self-servo writing using control circuitry that includes motor, actuator, and dual-phase driver circuits to simultaneously control multiple heads, enabling simultaneous reading and writing on multiple storage medium surfaces, with separate actuator control signals for each head and switchable modes for efficient servo track writing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional sequential self-servo writing is used, then hardware complexity remains low, but manufacturing time increases significantly

Engineering Contradiction:

Improvemanufacturing timeVSAvoidhardware complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The control circuit is designed to perform multiple functions: it can control single-head sequential self-servo writing and dual-head parallel self-servo writing modes. The circuit includes dual-phase driver circuits that can be selectively activated to drive actuators for different heads, allowing the same hardware to handle both sequential and parallel operations without requiring separate dedicated control circuits for each mode.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The control circuit dynamically switches between different operational modes (single-head sequential and dual-head parallel) based on the self-servo writing process requirements. The circuit can dynamically activate or deactivate specific driver circuits and actuators depending on whether parallel or sequential writing is needed, providing flexible adaptation to different process stages.

Inventive Principle:

Principle #15Dynamics

2Productivity

If parallel self-servo writing with multiple heads is implemented, then productivity improves, but the cost of specialized control circuitry increases

Engineering Contradiction:

Improveself-servo writing speedVSAvoidmanufacturing cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The control circuit is designed to perform multiple functions: it can control single-head sequential self-servo writing and dual-head parallel self-servo writing modes. The circuit includes dual-phase driver circuits that can be selectively activated to drive actuators for different heads, allowing the same hardware to handle both sequential and parallel operations without requiring separate dedicated control circuits for each mode.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the control functions for multiple heads into a single integrated control circuit. Instead of having separate control circuits for each head, the design combines dual-phase driver circuits that can be shared between heads, reducing the overall component count and manufacturing cost while enabling parallel operation capability.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If specialized external control circuitry is added for parallel self-servo writing, then parallel writing capability is achieved, but device complexity and cost increase

Engineering Contradiction:

Improveparallel writing capabilityVSAvoidcontrol circuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The control circuit is designed to perform multiple functions: it can control single-head sequential self-servo writing and dual-head parallel self-servo writing modes. The circuit includes dual-phase driver circuits that can be selectively activated to drive actuators for different heads, allowing the same hardware to handle both sequential and parallel operations without requiring separate dedicated control circuits for each mode.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The control circuit is designed to be self-sufficient for parallel self-servo writing operations without requiring external specialized control circuitry. The onboard control circuit includes integrated dual-phase driver circuits and actuator control capabilities that enable parallel writing functionality to be achieved using existing HDD control architecture, eliminating the need for additional external control hardware.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS12361968B1Servo interface circuitry for parallel self-servo write

Publication Date: 2025.07.15 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

Example servo interface circuitry, data storage devices, and methods to provide parallel self-servo write in a data storage device are described. The data storage device may include servo control circuitry that includes at least three digital-analog converters to provide control signals to the voice control motor (VCM) and arm actuators (e.g., micro actuators and milli actuators) of the data storage device. In data read/write mode, one actuator control signal controls the milli actuator for the target arm/head and another actuator control signal controls the micro actuator for the target arm/head. In self-servo write mode, one actuator control signal controls the micro actuator for one target arm/head and the other actuator control signal controls the micro actuator for another target arm/head for parallel self-servo writing.