Multi-Shield Capacitive Sensing Circuit for Accurate Proximity Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current capacitive touch sensing technologies face challenges in accurately detecting proximity at distant areas of mobile devices using a single sensing IC, as they struggle with maintaining shielding planes at the same voltage potential, leading to reduced accuracy and increased interference from RF and noise.
Innovation Solution
A capacitive touch controller with multiple sensing terminals and separate shielding terminals, which allows for independent voltage control of each shielding area, reducing the load on the sensing IC and minimizing interference between shielding areas, thereby enhancing accuracy and noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sensing IC is used to detect proximity at distant areas, then device complexity is reduced, but measurement precision deteriorates due to inability to maintain shielding planes at same voltage potential
Solution Approach 1:
The patent divides the single sensing IC into multiple independent sensing terminals, each with its own shielding terminal. This segmentation allows each sensing area to have independent voltage control, maintaining measurement precision while reducing overall device complexity compared to using multiple separate ICs.
Solution Approach 2:
The patent adds a new dimension of control by providing separate shielding terminals for each sensing terminal. This dimensional expansion in the control architecture enables independent voltage management of shielding planes, resolving the precision-loss problem without requiring multiple ICs.
2Device complexity
If shielding planes are shared across multiple sensing areas, then device complexity is reduced, but harmful factors increase due to RF and noise interference between areas
Solution Approach 1:
The patent segments the shared shielding structure into separate shielding terminals, each dedicated to a specific sensing area. This segmentation isolates RF and noise interference between areas while maintaining a unified shielding architecture, reducing harmful factors without excessive complexity.
Solution Approach 2:
The patent provides shielding coverage for each sensing area independently through separate terminals, ensuring adequate shielding performance for each region without over-engineering the entire system. This partial action approach optimizes the balance between complexity and interference reduction.
3Measurement precision
If multiple sensing ICs are used to maintain shielding planes independently, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple sensing functions into a single integrated sensing IC, while providing separate shielding terminals for each sensing area. This consolidation reduces device complexity and cost compared to using multiple ICs, while maintaining independent voltage control capability for precision measurement.
Solution Approach 2:
The single sensing IC is designed with multi-functionality, incorporating multiple sensing terminals and separate shielding terminals that can independently control voltage for each sensing area. This universal design achieves the precision of multiple ICs while maintaining the simplicity of a single device.
4Device complexity
If shielding areas are connected to a common terminal, then device complexity is reduced, but loss of energy increases due to reduced ability to maintain voltage potential
Solution Approach 1:
The patent segments the common terminal connection into separate shielding terminals, each independently connected to its sensing area. This segmentation reduces the total load on each terminal, improving voltage maintenance capability and reducing energy loss while keeping the terminal structure relatively simple.
Solution Approach 2:
The patent provides dedicated shielding terminals for each sensing area, ensuring adequate voltage maintenance for each region without over-provisioning the entire system. This partial action approach optimizes energy efficiency by matching shielding resources to actual sensing requirements.
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 enables more accurate and reliable capacitive touch sensing across multiple areas of a mobile device, reducing the need for multiple sensing ICs and minimizing interference, thus improving the overall performance and reducing the physical and cost constraints of mobile device design.
Implementation Method 1
Proximity sensor 11 uses the self-capacitance of a sensing element to determine whether a user is in proximity. Self-capacitance of the sensing element changes as a user's body part moves nearby proximity sensor 11.
Implementation Method 2
Capacitive sensing elements often use shielding areas to reduce the sensitivity to noise. The shielding areas are driven by the sensing IC to approximately the same voltage potential as an associated sensing element when detecting proximity.
Implementation Method 3
Touchscreen 12 utilizes resistance, capacitance, acoustic waves, an infrared grid, optical imaging, or other methods to determine the presence and location of a user's touch.
Data Source
Figure 1a~1b
Figure 1c
Figure 2a~2b
AI summary
A proximity sensor includes a capacitive touch controller. A first shielding area is coupled to a first shield terminal of the capacitive touch controller. A second shield area is coupled to a second shield terminal of the capacitive touch controller. A first sensing element is disposed adjacent to the first shielding area. The first sensing element is coupled to a first sensing terminal of the capacitive touch controller. A second sensing element is disposed adjacent to the second shielding area. The second sensing element is coupled to a second sensing terminal of the capacitive touch controller. The capacitive touch controller is configured to associate the first sensing element with the first shielding area. A self-capacitance of the first sensing element is measured while the second shielding area is inactive. The self-capacitance of the first sensing element is measured at a first frequency.