RX Electrode Layout for Capacitive Touch Noise Rejection
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Solution Overview
Problem
Conventional capacitive touch sensors experience weak Coulomb forces between segmented electrodes and are susceptible to external noise, leading to inefficiencies in noise immunity.
Innovation Solution
The design incorporates an RX electrode with a loop antenna shape formed by conductors arranged in a specific configuration, where external noise induces current flows in opposite directions, offsetting electric fields and reducing susceptibility to noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If three segmented electrodes are used in conventional capacitive touch sensors, then the electrode structure is simplified, but the sensor becomes susceptible to external noise due to weak Coulomb forces between adjacent electrodes
Solution Approach 1:
The RX electrode is divided into multiple conductors (first conductor, second conductor, third conductor, fourth conductor) arranged in a specific configuration. These segmented conductors work together to create opposing electric fields that cancel external noise, while maintaining electrical connectivity through the third and fourth conductors that extend in the array direction.
Solution Approach 2:
The conductors are arranged with specific asymmetric positioning where the first and second conductors are located close to each other with a gap, while the third and fourth conductors connect their respective ends. This asymmetric arrangement creates differential electric field patterns that enhance noise rejection capabilities while maintaining signal detection functionality.
2Object-affected harmful factors
If conductors are arranged close together to form loop antenna shape, then noise immunity is improved through offsetting electric fields, but manufacturing precision requirements increase
Solution Approach 1:
The third and fourth conductors connect corresponding ends of the first and second conductors, creating equipotential relationships that stabilize the electric field distribution. This helps maintain consistent noise rejection performance even with variations in the gap distance between adjacent conductors, reducing the impact of manufacturing tolerances.
Solution Approach 2:
The patent specifies that the maximum distance in the array direction between adjacent conductors should be 0.05 mm or larger, providing a minimum threshold that ensures adequate noise rejection while accommodating manufacturing variations. This parameter specification balances noise immunity requirements with practical manufacturing capabilities.
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 enhances noise immunity by reducing radiation and reception efficiency as a loop antenna, thereby improving the capacitive touch sensor's resistance to external noise.
Implementation Method 1
application of external noise to the electrode body induces current flows in opposite directions through the first and second conductors
Implementation Method 2
there are weak Coulomb forces generated between adjacent ones of the three segmented electrodes
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
The invention provides an RX electrode for a capacitive touch sensor that is less susceptible to external noise. An RX electrode 200 includes an electrode body 210 and a fourth conductor 214. A first conductor 211 and a second conductor 212 of the electrode body 210 extend in the X-X' direction and are located close to each other with a gap therebetween in the Y-Y' direction. Application of external noise to the first conductor 211 and the second conductor 212 in current flows in opposite directions through the first conductor 211 and the second conductor 212, and an electric field generated in the first conductor 211 and an electric field generated in the second conductor 212 offset each other. A third conductor 213 is connected to a first end portion 211a of the first conductor 211 and a first end portion 212a of the second conductor 212. The fourth conductor 214 is connected to a second end portion 211b of the first conductor 211 and a second end portion 212b of the second conductor 212.