Force-Sensing Touchpad Spring Structure for Bending Error Reduction
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Solution Overview
Problem
Capacitive force transducers in computing devices face errors in force calculations due to component bending, environmental factors, and manufacturing variabilities, which affect the accuracy of force sensing touchpads.
Innovation Solution
The implementation of a 'bucket-less' design that combines spring electrodes and resilient structures within the same footprint, reducing bending errors and packaging space, and utilizing differential capacitive sensing techniques for self-calibration to accommodate changes over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacitive force transducers are used with separate bucket and spring components, then the structure is simpler to manufacture, but bending errors and manufacturing variabilities reduce measurement precision
Solution Approach 1:
The patent merges the spring and bucket components into a single integrated structure where the spring forms the bucket. This integration eliminates the interface between separate components, removing the source of bending errors and manufacturing variabilities that affected measurement precision in traditional designs.
Solution Approach 2:
The spring structure serves multiple functions simultaneously: it provides mechanical support, enables capacitive sensing, and forms the bucket structure. This multi-functionality reduces the number of separate components needed while maintaining or improving measurement accuracy.
2Area of stationary object
If spring and bucket are integrated into the same footprint, then packaging space is reduced, but manufacturing precision requirements increase
Solution Approach 1:
By combining the spring and bucket into the same footprint, the patent reduces the overall packaging space required for the force transducer while integrating multiple functions into a compact structure.
3Reliability
If component bending is reduced through integration, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The integration of spring and bucket eliminates the interface where bending errors occurred in separate-component designs. This merging improves reliability by removing the source of measurement errors while the overall device complexity remains manageable due to the straightforward integrated structure.
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 configuration enhances the accuracy of force sensing by reducing bending errors and allowing for periodic calibration, thereby improving the reliability and efficiency of force detection in touchpads.
Implementation Method 1
the touchpad utilizes capacitance measurements to estimate a force applied to the touchpad
Implementation Method 2
A spring mounted on the base plate overlying the aperture in the base plate
Data Source
AI summary
Force sensing touchpads and related computing devices are disclosed. In one example, a force sensing touchpad comprises a printed circuit board (PCB) comprising a plurality of PCB electrodes. A base plate is spaced from the PCB and defines an aperture. A spring is mounted on the base plate overlying the aperture in the base plate. The spring comprises a plurality of spring electrodes, a first beam extending from a first internal wall to a first side of a central portion that overlies the aperture, and a second beam extending from a second internal wall that is opposite the first internal wall to a second side of the central portion that is opposite to the first side. A spacer located between the PCB and the central portion of the spring. Each of the PCB electrodes is spaced from and overlies one of the spring electrodes of the spring.