Trackpad Capacitive Force Sensor Haptic Feedback Decoupling
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Solution Overview
Problem
Existing trackpads face challenges in decoupling haptic feedback components from capacitive force sensors, leading to limitations in providing localized and effective tactile feedback while detecting user input and position accurately.
Innovation Solution
The trackpad architecture includes a haptic feedback component decoupled from the capacitive force sensor, with a spring element and spacer system that allows for independent movement, using a coil and magnet setup to provide haptic feedback through the substrate, and a dielectric to prevent damage to the circuit board during displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the haptic feedback component and capacitive force sensor are integrated together, then the device complexity is reduced, but the measurement precision and reliability of force detection deteriorates due to interference between the components
Solution Approach 1:
The trackpad is divided into separate functional modules: a capacitive force sensor assembly for detecting user input force and a haptic feedback assembly for providing tactile feedback. These modules are physically separated to prevent interference, with the force sensor containing a first plate and the haptic feedback containing a second plate, allowing independent optimization of each function while maintaining overall system integration
2Volume of moving object
If the haptic feedback component is positioned close to the capacitive force sensor, then the device compactness is improved, but the reliability of the circuit board deteriorates due to risk of damage during displacement
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the first plate of the capacitive force sensor and the second plate of the haptic feedback component. This dielectric layer acts as a protective barrier that prevents direct contact and potential damage between the circuit board components and the moving haptic feedback elements, thereby maintaining circuit board reliability while allowing the components to be positioned in close proximity for compact design
3Ease of operation
If the spring element is made more flexible to facilitate movement, then the ease of operation is improved, but the strength of the structure deteriorates due to reduced support for the circuit board
Solution Approach 1:
The spacer structure is designed with non-uniform properties: it includes a flexible portion that can deform to facilitate substrate movement and improve ease of operation, while simultaneously providing a rigid support portion that maintains structural strength and supports the circuit board. This local differentiation of mechanical properties allows the spacer to perform both flexible movement and structural support functions
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 enables effective localized haptic feedback and accurate force detection, allowing for improved user interaction with enhanced tactile sensations and reduced risk of circuit board damage.
Implementation Method 1
detecting a force applied to the substrate using a capacitive force sensor that detects a capacitance of the first plate and the second plate
Implementation Method 2
A coil of the haptic feedback component is mounted to one of the circuit board and the second plate, and a magnet of the haptic feedback component is mounted to another of the circuit board and the second plate, the haptic feedback component providing haptic feedback through the substrate using the coil and the magnet
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; a haptic feedback component coupled to the circuit board; a first plate coupled to the circuit board; a second plate including a spring element, a spacer coupling the circuit board and the spring element to each other, the spring element facilitating first movement of the substrate, the circuit board and the first plate relative to the second plate, the spacer facilitating second movement of at least the substrate and the circuit board by the haptic feedback component; and a capacitive force sensor that detects a capacitance of the first plate and the second plate. A trackpad can include a circuit board coupled to the substrate and including the first plate.