Capacitive Force Sensing Trackpad with Decoupled Spring Mechanism
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Solution Overview
Problem
Existing trackpads lack effective decoupling between capacitive force sensing and haptic feedback components, leading to limited movement and potential damage to circuit boards during force detection and feedback operations.
Innovation Solution
A trackpad architecture that includes a substrate, a circuit board with a capacitive force sensor, and a spring element facilitating movement between the circuit board and a second plate, with a dielectric and foam disc to prevent damage and allow decoupled movement for force sensing and haptic feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the circuit board is directly coupled to the substrate for force sensing, then force detection precision is improved, but the circuit board may be damaged during haptic feedback operations
Solution Approach 1:
A decoupling mechanism is introduced between the circuit board and substrate, consisting of a first plate coupled to the circuit board, a second plate coupled to the substrate, and a spring element connecting them. This intermediary structure allows force sensing while protecting the circuit board from damage during haptic feedback operations.
Solution Approach 2:
The coupling structure is divided into separate components: a first plate attached to the circuit board, a second plate attached to the substrate, and a spring element connecting them. This segmentation allows independent movement of each component, enabling force detection while protecting the circuit board.
2Ease of operation
If haptic feedback components are directly mounted to the substrate, then feedback effectiveness is improved, but movement of the substrate and circuit board is constrained
Solution Approach 1:
The spring element acts as an intermediary between the circuit board and substrate, allowing the substrate to move independently for effective haptic feedback while maintaining the electrical connection needed for force sensing.
Solution Approach 2:
The spring element provides dynamic coupling between the circuit board and substrate, allowing movement in response to haptic feedback forces while maintaining the structural connection needed for force detection.
3Adaptability or versatility
If the spring element facilitates movement between the circuit board and second plate, then decoupled movement is enabled, but device complexity increases
Solution Approach 1:
The spring element serves multiple functions: it provides mechanical coupling between the circuit board and substrate, enables decoupled movement for both force sensing and haptic feedback, and protects the circuit board from damage. This multi-functionality reduces the need for additional separate components.
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
Enables precise force detection and localized haptic feedback without damaging the circuit board, providing enhanced user interaction and feedback capabilities.
Implementation Method 1
a capacitive force sensor that detects a capacitance of the first plate and the second plate
Implementation Method 2
the spring element facilitating first movement of the substrate and the circuit board relative to the second plate
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A trackpad includes: a substrate; a circuit board coupled to the substrate for detecting a position of an object adjacent the substrate, the circuit board including a first plate; a second plate including a spring element, wherein a spacer couples the circuit board and the spring element to each other, the spring element facilitating first movement of the substrate and the circuit board relative to the second plate; and a capacitive force sensor that detects a capacitance of the first plate and the second plate. A trackpad can include a spacer coupling the circuit board and the spring element to each other, and facilitating second movement of at least the substrate and the circuit board by a haptic feedback component.