Touch Sensor Circuit Timing for Faster Reliable Detection
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Solution Overview
Problem
Touch sensors face challenges in accurately detecting touch events due to non-ideal factors such as touch strength, noise, and electromagnetic interference, often requiring multiple measurements which can lead to slow response times.
Innovation Solution
A circuit arrangement for a touch sensor that includes multiple capacitive sensors and a controller to efficiently measure capacitance across distinct regions, utilizing a scan mode and touch-event-determination mode to quickly and accurately detect touch events by synchronizing sampling and conversion periods and making consecutive measurements only when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple capacitance measurements are taken to verify touch events, then reliability of touch detection is improved, but response time deteriorates
Solution Approach 1:
The patent implements periodic scanning of the surface with multiple scan results averaged to determine touch events. The controller performs repeated capacitance measurements at different locations and times, then processes these periodic measurements to verify genuine touch events while filtering out transient noise or false signals.
Solution Approach 2:
The patent applies filtering operations to each scan result before final touch determination. By pre-processing the capacitance data through filtering algorithms, the system prepares the measurements in advance, reducing the computational burden during final touch verification and enabling faster response while maintaining reliability.
2Area of stationary object
If multiple capacitive sensors are activated simultaneously, then measurement coverage is improved, but resource utilization deteriorates
Solution Approach 1:
The patent divides the surface into multiple distinct regions and assigns different capacitive sensors to monitor different regions. The controller selectively activates specific capacitive sensors based on which regions need monitoring, rather than activating all sensors simultaneously. This segmentation approach ensures comprehensive coverage while optimizing resource utilization by activating only the necessary sensors.
Solution Approach 2:
The patent implements dynamic control of capacitive sensor activation, where the controller adjusts which sensors are active based on real-time requirements. The system can switch between different sensor configurations and activation patterns depending on the scanning phase and detected conditions, optimizing the balance between coverage and resource usage.
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
The solution enhances the speed and accuracy of touch event detection by minimizing unnecessary measurements, improving responsiveness in noisy environments while maintaining robustness against interference.
Implementation Method 1
a circuit arrangement configured to determine the capacitance of a plurality of distinct regions of a surface for determining the occurrence of a touch event
Data Source
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AI summary
A circuit arrangement for a touch sensor comprising: a plurality of capacitive sensors configured to measure over a respective sampling period for detecting a touch event on a surface and provide an output; an ADC to receive the output of the capacitive sensors and determine a digital value over a conversion period; a first switch arrangement configured to selectively provide the output from the capacitive sensors to the ADC; a controller configured to: activate a first capacitive sensor to measure the capacitance for detecting a touch event and activate a second capacitive sensor for detecting a touch event such that the respective sampling periods are at least partly concurrent, and configured to control the first switch arrangement to cause the ADC to receive the output of the first capacitive sensor after its sampling time and receive the output of the second capacitive sensor after its sampling time.