Capacitive Keypad Integrating Touch and Press Signals
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Solution Overview
Problem
The increasing miniaturization of electronic devices requires smaller and cost-effective user interfaces, but current keypad designs with both press and touch keys necessitate two flexible printed circuit boards and controllers, increasing size and cost.
Innovation Solution
A capacitive sensor element with a substrate and domes that generate distinct signals for touch and press key activations, allowing both key types to be integrated on a common flexible printed circuit board with a single controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If both press keys and touch keys are integrated in a keypad assembly, then the user interface provides rich features, but the size and cost of the assembly increase due to requiring two separate flexible printed circuit boards and two controllers
Solution Approach 1:
The patent combines both press key and touch key functionality into a single flexible printed circuit board by integrating a capacitive sensor element with a dome structure. The capacitive sensor element includes electrodes that form capacitors, where the dome acts as a movable electrode. This unified design eliminates the need for separate circuit boards and controllers for each key type, thereby reducing assembly complexity while maintaining versatile user interface features.
Solution Approach 2:
The capacitive sensor element serves multiple functions: it detects both touch events (when an object approaches or touches the electrode) and press events (when the dome is depressed, changing the capacitor configuration). This multi-functional sensor replaces what would traditionally require separate touch and press key mechanisms, allowing a single component to handle diverse input modes.
2Ease of operation
If two separate controllers are used for press keys and touch keys, then each key type can be controlled independently, but the overall device size and manufacturing cost increase
Solution Approach 1:
The patent merges the control functions for both press and touch keys into a single controller by using a unified capacitive sensor element. The sensor generates distinct signals for touch events and press events, allowing one controller to differentiate and process both key types independently through signal analysis, thereby reducing component count and manufacturing cost.
Solution Approach 2:
The single capacitive sensor element is designed to provide multiple control signals (touch signal and press signal) that can be processed by a universal controller. This multi-functional approach allows one controller to handle both key types with independent control capabilities, eliminating the need for separate dedicated controllers.
3Reliability
If dedicated flexible printed circuit boards are provided for each key type, then key functionality is reliable, but the assembly thickness and device size increase
Solution Approach 1:
The patent merges both press key and touch key structures into a single flexible printed circuit board assembly. The capacitive sensor element with its electrode and dome configuration is integrated directly onto the board, eliminating the need for multiple stacked circuit boards. This integration maintains reliable key functionality while significantly reducing the overall assembly thickness.
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 solution reduces the size and cost of keypad assemblies by eliminating the need for dedicated circuit boards and controllers for each key type, enabling thinner and more economical mobile devices.
Implementation Method 1
a capacitive sensor element having a first electrode forming a first capacitor with an object touching or coming into proximity of the first electrode
Implementation Method 2
a dome configured to complete, responsive to the dome being depressed, an electric circuit comprising at least the first capacitor and the first capacitor circuit to form a second capacitor circuit
Data Source
AI summary
The disclosure relates to implementing different key types on a keypad or keyboard. The implementation can be enabled e.g. by an apparatus including a substrate (28) including a capacitive sensor element (29), the capacitive sensor element having a first electrode (24) forming a first capacitor with an object touching or coming into proximity of the first electrode, wherein the capacitive sensor element is configured to generate a first signal responsive to the object touching or coming into proximity of the capacitive sensor element, a first capacitor circuit coupled to at least the first electrode, and a dome (26) configured to complete, responsive to the dome being depressed, an electric circuit including at least the first capacitor and the first capacitor circuit to form a second capacitor circuit, wherein the second capacitor circuit is configured to generate a second signal.