Spindle Motor Deceleration via Dynamic Braking
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Solution Overview
Problem
Disk drives in mobile electronic devices face mechanical shock events that can cause disk deflection and contact with other components, leading to particulate matter generation, which affects the operation and reliability of the drive.
Innovation Solution
Implementing a spindle motor deceleration process that includes controlled braking and dynamic braking to reduce the angular velocity of disks before a mechanical shock event, using a servo controller to apply negative torque and electrical shorts to windings, respectively, to minimize particulate matter generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the spindle motor maintains high angular velocity during operation, then data read/write performance is improved, but particulate matter generation increases during mechanical shock events
Solution Approach 1:
The system performs preliminary deceleration action by detecting mechanical shock events (via accelerometer or drop detection circuit) and activating the spindle motor braking mechanism before the shock reaches critical intensity. This preliminary action reduces the angular velocity of the spindle motor to a safe threshold level, preventing disk deflection and particulate matter generation while maintaining normal operation during non-shock conditions.
2Object-generated harmful factors
If the spindle motor is quickly stopped during shock, then particulate matter generation is reduced, but mechanical stress on components increases
Solution Approach 1:
The braking mechanism dynamically adjusts the deceleration rate based on the intensity and duration of the detected shock event. The control circuit modulates the braking force applied to the spindle motor, providing gentle deceleration for minor shocks and more aggressive braking for severe shocks. This dynamic approach reduces particulate matter generation while minimizing mechanical stress on disks and components.
3Speed
If a braking mechanism is added to the spindle motor, then deceleration capability is improved, but device complexity increases
Solution Approach 1:
The braking mechanism is integrated with the existing spindle motor control circuitry, allowing the same control hardware to perform both normal motor operation and emergency braking functions. The accelerometer/drop detection circuit shares the microcontroller or control unit that manages spindle motor operation, eliminating the need for separate dedicated braking control hardware and minimizing added complexity.
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
The spindle motor deceleration process effectively reduces the angular velocity of disks before impact, thereby decreasing particulate matter generation and enhancing the reliability of the disk drive during mechanical shock events.
Implementation Method 1
a spindle motor (SM) for rotating disks (102, 104)... causing a negative torque to be applied to the rotor (106) of the spindle motor (138)
Implementation Method 2
dynamic braking... causing an electrical short to be applied across windings of the spindle motor (138)
Data Source
AI summary
A spindle motor of a disk drive includes a stator with windings and a rotor configured to rotate a disk of the disk drive. It is determined whether the disk drive is in a falling state while the disk rotates, and when the disk drive is in the falling state, a negative torque is applied to the rotor to reduce an angular velocity of the disk. When the angular velocity of the disk reaches a threshold angular velocity, an electrical short is caused across the windings of the stator to further reduce the angular velocity of the disk.