Tamper-Resistant Keypad with Captured Actuator Flanges
Solution Overview
Problem
Bezel-less keypads in mobile devices are susceptible to damage due to the risk of users inserting objects between keys, which can dislodge them, compromising the structural integrity and functionality.
Innovation Solution
A tamper-resistant keypad design featuring actuators with flanges that are mechanically captured by a frame, preventing removal and ensuring keycaps remain securely attached, while also utilizing a gasket and contact domes on a printed circuit board for tactile feedback and activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a bezel-less keypad design is used to make keys larger, then key size is improved, but susceptibility to damage from object insertion worsens
Solution Approach 1:
The actuator is divided into distinct segments: a shaft portion extending through the frame, a head portion at the first end coupled to the keycap, and a flange at the second end. This segmentation allows each part to serve its specific function while collectively providing tamper resistance without requiring bezels around each key.
Solution Approach 2:
The solution moves from a two-dimensional planar restraint (bezel surrounding the key) to a three-dimensional constraint system. The flange with its protrusion extending laterally from the shaft creates a vertical dimension of restraint, where the protrusion engages with a recess in the frame to prevent removal from the opposite side.
2Strength
If framed keypads are used to provide structural support, then structural integrity is improved, but key size worsens
Solution Approach 1:
The invention extracts the structural support function from the traditional bezel/frame surrounding each key and relocates it to the actuator-flange-frame assembly. This allows the keycap to extend fully to the edges without compromising structural integrity, as the actuator mechanism itself provides the restraint.
3Ease of manufacture
If traditional membrane keypads with rubber overlays are used, then manufacturing simplicity is improved, but tamper resistance worsens
Solution Approach 1:
The flange acts as an intermediary component between the actuator shaft and the frame. It provides a simple mechanical engagement feature (protrusion and recess) that prevents removal while maintaining ease of manufacture. The flange can be integrally formed with the actuator or separately attached, offering manufacturing flexibility.
Data Source
AI summary
A tamper-resistant keypad is described. The keypad includes a keycap for actuation by a user. An actuator includes a first end that is coupled to the keycap. A frame having an aperture is adapted to receive the actuator such that the second end of the actuator is captured by the frame. The actuator is prevented from being removed from the frame.