Keyboard Force Sensor Zoning for Uniform Key Sensitivity
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Solution Overview
Problem
Achieving uniform force sensitivity across a keyboard employing force sensitive technology is challenging due to variations in keycap sizes, shapes, and positions, which affect the force response of keys.
Innovation Solution
The force sensing apparatus divides the membrane into sections, grouping FSR sensels with similar resistance ranges together and connecting them to dedicated input channels. Each sensel group has a corresponding control module tuned to operate within the group's resistance range, allowing for precise force signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a membrane with matrix structure and keys at intersections is used for force sensing, then force sensitivity can be achieved, but variations in keycap sizes, shapes, and positions cause non-uniform force sensitivity across the keyboard
Solution Approach 1:
The keyboard is divided into multiple zones, with each zone containing keycaps of similar sizes and characteristics. Each zone is assigned a dedicated control module that is tuned to the specific resistance range of that zone's sensels, allowing uniform force sensitivity measurement within each zone despite variations across the entire keyboard
Solution Approach 2:
Different control modules are configured with different tuning parameters optimized for local zones of the keyboard. Each control module has resistance range settings matched to the specific keycap characteristics (size, shape, position) of its associated zone, enabling precise force sensitivity measurement tailored to each local region
2Measurement precision
If all sensels are connected to a single control module, then device complexity is reduced, but measurement precision deteriorates due to inability to account for variations in keycap characteristics
Solution Approach 1:
The control system is segmented into multiple control modules, each responsible for a specific zone of the keyboard. This segmentation allows each module to be optimized for its local zone while maintaining overall system functionality
Solution Approach 2:
Control modules differ in their operating parameters, specifically their tuned resistance ranges. Each module's parameters are changed to match the characteristics of its associated zone, enabling precise measurement without requiring identical complex configurations across all modules
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 approach enables improved force detection sensitivity and consistency across the keyboard by tailoring the measurement electronics to the specific properties of each sensel group, enhancing user experience and flexibility in design.
Implementation Method 1
each sensel is configured to exhibit a variable resistance response in dependence on a magnitude of a force applied to the sensel
Data Source
AI summary
Examples disclosed relate to force sensing apparatus and methods of manufacture. A force sensing apparatus includes drive lines and sensing lines arranged to provide intersections, each of the intersections defining a sensel, wherein each sensel is configured to exhibit a variable resistance response in dependence on a magnitude of a force applied to the sensel. The sensels are grouped in multiple sensel groups and each of the sensels in a sensel group is configured to exhibit a variable resistance response within a group resistance range. The group resistance range of a first sensel group is different to the group resistance range of a further sensel group. The force sensing apparatus includes control modules, each of the control modules connected to a corresponding sensel group and configured to output a force signal indicative of a force applied to a sensel in the corresponding sensel group.