Lid Sensor Debouncing for Portable IHS Stability
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Solution Overview
Problem
Portable information handling systems often experience system instability and freezing due to frequent false signals generated by lid sensors when the lid is left slightly open, causing multiple signals to be sent to the operating system, leading to system inoperability.
Innovation Solution
Implementing a dual timing method that prevents additional signals from being received if a predetermined time has not elapsed since the last lid position change, thereby debouncing the lid sensor fluctuations and reducing system instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the lid sensor continuously reports lid position changes to the operating system, then the system responds quickly to lid opening/closing actions, but the system becomes unstable and may freeze due to multiple rapid signals from sensor bounce
Solution Approach 1:
The system performs preliminary filtering of sensor signals by implementing a debounce mechanism that waits for a predetermined time period (e.g., 1 second) after detecting a lid position change before accepting subsequent signals. This preliminary action prevents immediate re-triggering of system operations due to sensor bounce, thereby maintaining system stability while preserving legitimate user actions.
Solution Approach 2:
The system implements feedback control by continuously monitoring the lid sensor and comparing current readings with previous states. When the lid position changes, the system enters a feedback loop that suppresses further signals within a predetermined time window. This feedback mechanism ensures that only stable, deliberate lid position changes are processed, preventing system freezing while maintaining responsive operation.
2Reliability
If the system implements a timing mechanism to filter multiple signals, then system stability is improved by preventing signal bounce, but the response time for legitimate lid position changes may be delayed
Solution Approach 1:
The system dynamically adjusts the timing parameter (predetermined time period) based on the specific operational context. For example, the debounce time may be extended when the system is in a critical state or shortened when rapid response is needed. This parameter change allows the system to balance between filtering false signals and maintaining fast response to legitimate user actions, optimizing the trade-off between stability and responsiveness.
Data Source
AI summary
A method for reducing the receipt of multiple signals in a portable information handling system (IHS) is closed including receiving a first signal corresponding to a detected lid position of the portable IHS. The method further includes determining if a first predetermined amount of time has elapsed and if the first predetermined amount of time has not elapsed, preventing the receipt of an additional signal corresponding to a change in the detected lid position. Further, a portable information handling system may include a lid, a base coupled to the lid and a sensor disposed on the lid or base, wherein the sensor detects a lid position. The system further includes a processor coupled to the sensor, wherein the processor generates a first signal corresponding to the lid position and the processor is operable to generate an additional signal corresponding to a change in the lid position.