Capacitive Sensor Multiple Transmit Electrodes Sensitivity
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Solution Overview
Problem
Capacitive sensor systems, such as those used in touch screens, face limitations in sensitivity, restricting their application to larger display sizes and more demanding sensing requirements.
Innovation Solution
The implementation of multiple transmission electrodes with different voltage levels, where one electrode is driven with a higher alternating voltage than the others, enhances mutual and self-capacitance measurements without overdriving the sensing input, allowing for increased sensitivity and expanded application possibilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single transmitting electrode is used, then the device complexity is low, but the measurement precision is insufficient
Solution Approach 1:
The transmitting electrode is divided into multiple segments (first transmitting electrode and second transmitting electrode) that can be independently controlled. This segmentation allows different voltage levels to be applied to different segments, enhancing the electric field distribution and improving sensitivity without requiring a complete redesign of the entire electrode system.
Solution Approach 2:
Different segments of the transmitting electrode are assigned different voltage levels (the second transmitting electrode receives a higher alternating voltage than the first). This local differentiation of electrical properties creates optimized electric field zones that enhance capacitive coupling with the receiving electrode, thereby improving measurement precision in specific regions.
2Measurement precision
If higher voltage is applied to increase sensitivity, then the measurement precision improves, but the harmful factors increase due to overdriving the sensing input
Solution Approach 1:
By segmenting the transmitting electrode into multiple independently controllable segments, the patent enables selective application of voltage levels. The second transmitting electrode can be driven at a higher voltage to enhance sensitivity, while the first transmitting electrode operates at a lower voltage to avoid overdriving the sensing input, thus resolving the contradiction between sensitivity enhancement and harmful effects.
Solution Approach 2:
Different voltage levels are applied to different segments of the transmitting electrode based on their specific functional requirements. This localized voltage optimization allows the system to achieve high sensitivity where needed while maintaining safe operating levels in other regions, preventing overdriving of the sensing input.
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 approach increases the sensitivity of capacitive sensor systems by up to a factor of three, enabling new applications, including larger display sizes and combined 2D-3D input solutions, while avoiding overdriving issues and maintaining effective operation.
Implementation Method 1
a receiving electrode having a capacitive coupling to a ground plane or ground electrode
Implementation Method 2
generate an alternating electric near field and measure distortions of such a field
Data Source
AI summary
A capacitive sensor system has a receiving electrode with a capacitive coupling to a ground plane or ground electrode, a first transmission electrode arranged between the receiving electrode and the ground plane and having a size with respect to the receiving electrode such that the transmission electrodes covers a surface area of the receiving electrode, and a second transmission electrode arranged adjacent to the receiving electrode and which is not coupled with the first transmission electrode, wherein the second transmission electrode is driven with a higher alternating voltage than the first transmission electrode.