Friction Force Sensor for Head-Media Interface Spacing Control
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Solution Overview
Problem
In data storage devices, the close proximity of the head to the media to achieve higher recording densities increases the risk of head-media contact, leading to degraded read and write operations and potential damage.
Innovation Solution
A sensor device is employed to measure friction force at the head-media interface using a transducer element with in-plane axis orientation and sensor circuitry, which detects friction force through an actuator element's cyclic protrusion and power on/off frequency, allowing for real-time monitoring and control of head-media spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the head is positioned closer to the media to achieve higher recording densities, then the recording density is improved, but the risk of head-media contact increases
Solution Approach 1:
The friction force sensor provides advance detection of head-media contact conditions before actual contact occurs. By monitoring friction force changes in the air bearing, the system can predict impending contact and take preventive action, such as adjusting head position or reducing write current, thereby maintaining high recording density while preventing damage
Solution Approach 2:
The patent implements a feedback mechanism where the friction force sensor continuously monitors the interface between head and media, and this information is fed back to the control system. The controller adjusts operational parameters based on the friction force signals, creating a closed-loop system that maintains optimal head-media spacing for high-density recording while preventing contact
2Productivity
If the fly height of the head above the media is decreased to achieve higher recording densities, then the recording density is improved, but the propensity for head or media damage increases
Solution Approach 1:
The friction force sensor detects changes in friction force that precede actual head-media contact. By monitoring these preliminary friction force variations, the system can take preventive action before damage occurs, allowing the head to operate at lower fly heights for high-density recording without risking damage
Solution Approach 2:
The control system uses feedback from the friction force sensor to continuously adjust operational parameters. When friction force indicates approaching contact conditions, the system responds by modifying head position or operational parameters, enabling sustained high-density recording at low fly heights while preventing damage
3Measurement precision
If a sensor device with in-plane axis orientation is used to detect friction force, then the contact detection precision is improved, but the device complexity increases
Solution Approach 1:
The friction force sensor is integrated into the existing head assembly structure, serving multiple functions: it detects friction force for contact prediction, provides feedback for control systems, and utilizes the in-plane axis orientation that already exists in the head's mechanical structure. This multi-functionality approach improves measurement precision without proportionally increasing device complexity
Solution Approach 2:
The sensor device utilizes the inherent in-plane axis orientation of the head assembly, leveraging the existing structural features rather than requiring additional complex mounting mechanisms. The sensor integrates with the air bearing and head structure, using available space and structural elements to achieve precise friction force detection without adding significant 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
This solution effectively detects contact and maintains optimal head-media spacing, preventing damage and ensuring reliable read and write operations by providing a measure of friction force for active control, thus enhancing operational stability and reliability.
Implementation Method 1
a transducer element having a sensing axis orientated along an in-plane axis to provide an electrical output responsive to force or strain imparted to the transducer element
Implementation Method 2
The head includes an actuator element which is powered on/off at an on/off frequency to cyclically protrude a localized portion of the head
Data Source
AI summary
The application discloses a sensor device to measure friction force at a head-media interface. As disclosed, the sensor device has a transducer element oriented to provide an electrical output responsive to force or strain imparted to the transducer element along an in-plane axis. Sensor circuitry is coupled to the transducer element to process the electrical output to provide an output measure of friction force. In illustrated embodiments, the head includes an actuator element which is powered on/off at an on/off frequency to cyclically protrude a localized portion of the head. The on/off frequency of the actuator is used by the sensor circuitry to detect excitation of the sensor device due to friction force at the head-media interface.