Low-Profile Capacitive Pointing Stick with Compliant Gap
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Solution Overview
Problem
Existing input devices, such as pointing sticks and touchpads, face challenges in providing efficient and accurate control of user interface indicators on electronic devices, particularly in terms of spatial precision and capacitive sensing, especially in low-profile designs.
Innovation Solution
An isometric input device with a plurality of sensor electrodes on a sensor substrate, a control member mechanically coupled to the substrate, and a conductive support substrate with a compliant member, which measures changes in capacitive coupling between sensor electrodes and the conductive support substrate due to deflection of the control member, enabling precise control of user interface indicators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional pointing stick design is used, then mechanical control is provided, but spatial precision and capacitive sensing accuracy are insufficient
Solution Approach 1:
The patent combines mechanical control elements with capacitive sensing electrodes into an integrated structure. The sensor substrate includes both mechanical control members and sensor electrodes that work together, allowing the device to achieve both mechanical pointing control and capacitive sensing functionality without requiring separate devices, thereby improving spatial precision while managing complexity through integration.
Solution Approach 2:
The patent introduces a compliant member as an intermediary element between the sensor substrate and the conductive support substrate. This compliant member allows for precise measurement of deflection changes caused by user input, translating mechanical movements into measurable capacitive changes, thereby enhancing measurement precision without directly increasing overall device complexity.
2Length of stationary object
If a low-profile design is implemented, then device profile is reduced, but capacitive sensing capability is compromised
Solution Approach 1:
The patent measures capacitive coupling changes in a different dimension - by detecting changes in the gap distance between the sensor substrate and conductive support substrate through the compliant member's deflection. This allows the low-profile design to maintain capacitive sensing capability by measuring coupling changes rather than requiring large physical movements, thus resolving the contradiction between reduced profile and sensing capability.
Solution Approach 2:
The patent changes the measurement parameter from physical contact or large movement to subtle deflection-induced capacitive coupling changes. By measuring changes in capacitive coupling between sensor electrodes and the conductive support substrate through the compliant member's deflection, the system achieves sensitive detection in a low-profile configuration without compromising sensing capability.
3Ease of manufacture
If sensor electrodes are directly coupled to conductive support substrate, then manufacturing is simplified, but measurement precision of deflection is reduced
Solution Approach 1:
The patent introduces a compliant member as an intermediary between the sensor substrate and conductive support substrate. This intermediary element enables precise measurement of deflection changes by translating mechanical movements into measurable capacitive changes, while still allowing for relatively simple manufacturing processes. The compliant member acts as a bridge that maintains both manufacturing feasibility and measurement precision.
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
The solution provides enhanced precision and accuracy in controlling user interface indicators by effectively measuring changes in capacitive coupling, allowing for precise cursor movement and input detection without the need for physical contact, suitable for low-profile designs.
Implementation Method 1
measuring a change in capacitive coupling between at least one ohmically isolated conductive element and the conductive support substrate based on the resulting signals
Data Source
AI summary
In an example, an isometric input device configured to control a user interface indicator of an electronic device includes a plurality of sensor electrodes disposed on a sensor substrate. The input device further includes a control member mechanically coupled to the sensor substrate over at least a portion of the plurality of sensor electrodes. The input device further includes a conductive support substrate and a compliant member disposed between the sensor substrate and the conductive support substrate. The input device further includes a securing component extending through the conductive support substrate and the compliant member and engaging with the control member, the securing component defining a gap between the sensor substrate and the conductive support substrate.