Capacitive Touch Sensor Dynamic Mode Switching for Pen Latency
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Solution Overview
Problem
Capacitive touch sensors often prioritize finger detection over pen detection, leading to increased pen interaction latency and power consumption, and reduced signal-to-noise ratio (SNR), which degrades the user experience by delaying pen detection and communication.
Innovation Solution
Implementing operational modes that selectively use AC and DC drive signals to differentiate between finger and pen detection, reducing pen interaction latency and power consumption while maintaining high SNR, allowing for efficient detection and tracking of both inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the touch sensor prioritizes finger detection over pen detection, then finger detection accuracy is improved, but pen interaction latency increases and power consumption increases
Solution Approach 1:
The touch sensor system dynamically switches between different operational modes (first mode optimized for finger detection, second mode optimized for pen detection) based on the detected input type. This dynamic adaptation allows the system to optimize performance for the current input modality, reducing pen interaction latency when a pen is detected while maintaining high finger detection accuracy when a finger is present.
Solution Approach 2:
The system changes operational parameters (such as sampling rate, drive signal characteristics, and processing priority) based on the detected input type. When a pen is detected, the system transitions to a second operational mode with parameters optimized for pen communication, thereby reducing pen interaction latency while maintaining accurate finger detection capability when needed.
2Measurement precision
If the touch sensor prioritizes finger detection over pen detection, then finger detection accuracy is improved, but power consumption increases
Solution Approach 1:
The touch sensor system dynamically adjusts its operational mode based on the detected input type, switching between a first mode optimized for finger detection and a second mode optimized for pen detection. This dynamic adaptation allows the system to consume less power by using the pen-optimized mode when a pen is detected, while still maintaining high finger detection accuracy when a finger is present.
Solution Approach 2:
The system changes operational parameters including power consumption levels based on the detected input type. When a pen is detected, the system transitions to a second operational mode with reduced power consumption settings optimized for pen communication, thereby lowering overall power usage while maintaining accurate finger detection capability when needed.
3Device complexity
If the touch sensor uses a single operational mode, then device complexity is reduced, but pen detection performance and finger detection performance cannot both be optimized
Solution Approach 1:
The touch sensor system implements multi-functionality by incorporating multiple operational modes within a single device architecture. The first mode is optimized for finger detection while the second mode is optimized for pen detection and communication. This universal design allows the system to handle both input types with optimized performance for each, without requiring separate dedicated systems.
Solution Approach 2:
The system dynamically selects between different operational modes based on the detected input type, allowing a single touch sensor device to adapt its behavior for optimal finger detection or optimal pen detection/communication. This dynamic capability enables the system to maintain both optimized detection performances without permanently increasing hardware complexity.
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 enables reduced pen interaction latency and power consumption while maintaining high SNR, allowing for efficient detection and tracking of both fingers and pens, thereby enhancing the user experience by ensuring timely and accurate input recognition.
Implementation Method 1
a capacitive touch sensor to detect the presence of an input device such as a human finger or pen
Implementation Method 2
touch sensors drive electrodes with a time-varying AC voltage when attempting to detect a finger, so that the finger induces a change in electrode current
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
Examples are disclosed herein that relate to various operational modes of a capacitive touch sensor. One example provides a touch-sensitive input device comprising receive circuitry, a capacitive touch sensor having a plurality of portions, and a controller. The controller is configured to, responsive to not detecting a finger or a pen, operate the touch sensor in a locating mode by successively driving each portion with a fixed DC voltage and multiplexing the portion to the receive circuitry in a predefined sequence, and responsive to detecting the pen, operate the touch sensor in a tracking mode by driving a selected portion with the fixed DC voltage and multiplexing the selected portion to the receive circuitry to track the pen, the selected portion selected based on a detected location of the pen relative to the touch sensor and being varied as the detected location changes.