Keyboard Key Actuation Using Shape Memory Alloy Wires
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Solution Overview
Problem
Portable information handling systems face challenges in minimizing height while integrating keyboard keys, as physically-moving keys add vertical height and mechanical or electromechanical actuators used for retraction tend to fail due to mechanical stress over repeated use.
Innovation Solution
The system employs shape memory wire actuated by current to rapidly and reliably retract and extend keyboard keys, using a low-height structure with a keyboard manager that monitors conditions to manage current application, ensuring desired behavior and reducing wire wear, with shuttles interacting with sliding plates to overcome key biasing mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical or electromechanical actuators are used to retract keyboard keys, then key retraction is achieved, but the actuators fail due to mechanical stress over repeated use
Solution Approach 1:
The patent replaces mechanical or electromechanical actuators with shape memory alloy (SMA) wires that use thermal-mechanical coupling. When current passes through the SMA wires, they heat up and change shape, pulling the keys inward without mechanical moving parts. This substitution eliminates wear and failure associated with traditional actuators.
Solution Approach 2:
The patent changes the physical state of the shape memory alloy wires through temperature control. By applying current to heat the wires above their transformation temperature, the wires contract and retract the keys. When cooled below the transformation temperature, the wires extend back to their original length, allowing key protrusion without mechanical actuators.
2Ease of operation
If keyboard keys are made physically movable, then user feedback is improved, but vertical height increases
Solution Approach 1:
The patent moves the key retraction mechanism from the vertical dimension to the horizontal dimension. Instead of keys moving up and down within a tall housing, the keys move inward and outward horizontally using SMA wires. This allows full key travel for user feedback while maintaining a low-profile vertical height.
3Length of moving object
If key travel is reduced to minimize height, then vertical dimensions are reduced, but input speed and accuracy decrease
Solution Approach 1:
The patent provides full key travel distance by changing the direction of key movement from vertical to horizontal. The SMA wire mechanism allows keys to move the full distance needed for comfortable typing while keeping the vertical profile minimal, thus maintaining both compact size and input productivity.
4Reliability
If shape memory wire is used for key retraction, then actuator reliability is improved, but precise control of wire actuation is required
Solution Approach 1:
The patent incorporates feedback mechanisms to monitor and control the SMA wire actuation. Sensors detect key position and wire tension, providing feedback to the control system. This ensures precise control of the thermal-mechanical coupling process, preventing overheating and ensuring reliable key retraction and protrusion cycles.
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 efficient and repeatable key retraction and extension with minimal height impact, providing a robust and user-friendly experience by using shape memory alloys that endure repeated actuations and precise control based on detected conditions.
Implementation Method 1
shape memory wire actuated by current to rapidly and reliably retract and extend keyboard keys
Implementation Method 2
shape memory wire actuated by current to rapidly and reliably retract and extend keyboard keys
Data Source
AI summary
An information handling system integrated keyboard selectively retracts and extends keys based upon detected conditions, such as housing configuration, housing motion and end user indications. Extension and retraction shuttle plates motivated by actuator wires moves a sliding plate to extended and retracted positions that define the key positions. Nickel titanium alloy actuator wires shorten upon application of current to pull the shuttle plates to the extended or retracted positions that are maintained by a lock. Limit switches remove current at detection of a desired shuttle plate position. One or more controllers manage actuator wire operation based upon detected conditions and actuator wire temperature and electrical characteristics.