Force-Sensing Input Member for Partial and Full Press Feedback
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Solution Overview
Problem
Existing user input mechanisms in electronic devices lack the ability to differentiate between partial and full presses, and provide effective haptic feedback for both, especially when the device is powered off or without consuming power.
Innovation Solution
Integration of a strain sensor and a tactile switch with a haptic actuator in a user input member, where the strain sensor detects a partial press and triggers haptic feedback, and the tactile switch provides feedback upon a full press, using a deformable element transitioning between steady and semi-steady states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single force-sensing mechanism is used, then the device structure is simple, but it cannot differentiate between partial and full presses
Solution Approach 1:
The sensing mechanism is divided into two independent components: a strain sensor for detecting partial presses and a tactile switch for detecting full presses. Each component has its own actuation threshold, allowing the system to differentiate between different press depths without requiring a single complex sensing mechanism.
2Reliability
If continuous haptic feedback is provided, then user feedback is consistent, but power consumption increases
Solution Approach 1:
Haptic feedback is provided periodically based on discrete press events rather than continuously. The system activates haptic feedback only when the strain sensor or tactile switch detects a press, with the feedback duration matching the press duration. This event-driven approach maintains reliable user feedback while minimizing power consumption during idle periods.
3Adaptability or versatility
If multiple sensing mechanisms are integrated, then press differentiation is enabled, but device complexity increases
Solution Approach 1:
The strain sensor and tactile switch are integrated into a single user input member assembly, sharing common structural elements such as the button body, spring mechanism, and housing. This merging approach enables multiple press detection modes while minimizing the increase in overall device complexity through shared components and compact arrangement.
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 differentiation between partial and full presses with power-efficient haptic feedback, allowing for enhanced user input functionality and device operation, including special modes and camera functions, without continuous power consumption.
Implementation Method 1
The strain sensor may be positioned to experience strain as a force is applied to the user input surface
Implementation Method 2
The tactile switch may provide its haptic output as it transitions from the steady state to the semi-steady state
Implementation Method 3
a haptic feedback mechanism (e.g., a piezoelectric material) that provides an acknowledgement of the partial press
Data Source
AI summary
A strain-sensing device includes a flexible printed circuit and a strain sensor formed on the flexible printed circuit. The flexible printed circuit includes a stacked set of layers. Each layer in the stacked set of layers has a glass transition temperature (Tg) greater than 50 degrees Celsius (50° C.), and each pair of adjacent layers in the stacked set of layers has a Tg greater than 50° C. The stacked set of layers, as a whole, also has a Tg greater than 50° C.