Capacitive Touch Panel Single Sensor Active Passive Input
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Solution Overview
Problem
Current touch panel systems require separate sensors and controllers to detect both passive and active inputs, increasing cost and complexity, while existing solutions fail to efficiently sense active stylus inputs simultaneously with finger or passive stylus inputs.
Innovation Solution
A capacitive touch panel system using a single set of sensors and a single touch controller to detect both active and passive inputs, employing narrow band frequency response and IQ demodulation for improved signal-to-noise ratio and simultaneous sensing of multiple inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate sensors and controllers are used to detect passive and active inputs, then detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines passive and active input detection into a single sensor system. The same sensor array detects both finger touches (passive) and stylus inputs (active) by receiving signals from both sources simultaneously, eliminating the need for separate sensor systems while maintaining detection accuracy through signal differentiation techniques
Solution Approach 2:
The sensor system is designed to perform multiple functions: detecting passive finger inputs, active stylus inputs, and distinguishing between them. The single sensor system universally handles both input types by detecting signal characteristics and frequency differences, reducing overall system complexity
2Measurement precision
If separate sensors are used for active and passive inputs, then signal accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges passive and active input detection into one sensor system, reducing component count and manufacturing complexity. The controller processes both signal types through a unified detection pathway, simplifying assembly and reducing production costs while maintaining signal accuracy through digital signal processing
Solution Approach 2:
The system distinguishes between passive and active inputs by detecting signal frequency and amplitude parameters. The active stylus transmits signals at specific frequencies that differ from passive finger touches, allowing the single sensor system to accurately differentiate and process both input types based on their unique signal characteristics
3Device complexity
If a single sensor detects both active and passive inputs, then device complexity is reduced, but difficulty of detecting and measuring increases
Solution Approach 1:
The patent applies different detection strategies to different signal types within the same sensor system. The controller analyzes local signal characteristics such as frequency, amplitude, and temporal patterns to distinguish between passive finger inputs and active stylus inputs, making detection manageable through localized analysis techniques
Solution Approach 2:
The controller acts as an intermediary that processes and differentiates signals from both passive and active inputs. It uses signal processing algorithms to separate and identify the nature of each input based on their distinct electrical characteristics, reducing the complexity of direct detection by introducing an intelligent mediation layer
4Measurement precision
If narrow band frequency response and IQ demodulation are used, then signal-to-noise ratio is improved, but processing complexity increases
Solution Approach 1:
The patent transforms the detected signals through IQ demodulation, converting them into in-phase and quadrature components that separate signal information from noise. This parameter transformation allows narrow band filtering to effectively isolate the active stylus signals from background noise, improving signal-to-noise ratio while the processing complexity is managed through efficient digital signal processing algorithms
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 system achieves reduced cost and complexity by enabling simultaneous sensing of finger, passive stylus, and active stylus inputs with improved noise performance and signal accuracy, supporting high-frequency synchronization and pressure detection.
Implementation Method 1
each coordinate location comprises a capacitor formed at a junction between one of the drive electrodes and one of the sense electrodes via mutual capacitance between the electrodes
Implementation Method 2
Passive input can also be sensed via self-capacitance of the capacitive touch panel sensors
Implementation Method 3
The drive electrodes and the sense electrodes are configured to receive a second signal from an active stylus to sense active input to the capacitive touch panel at each coordinate location
Data Source
AI summary
A capacitive touch panel includes sense electrodes arranged next to one another and drive electrodes arranged next to one another across the sense electrodes. The drive electrodes and the sense electrodes define a coordinate system where each coordinate location comprises a capacitor formed at a junction between one of the drive electrodes and one of the sense electrodes via mutual capacitance between the electrodes. The drive electrodes are configured to receive a first signal from a driver coupled with the drive electrodes for powering the drive electrodes to sense passive input to the capacitive touch panel at each coordinate location. Passive input can also be sensed via self-capacitance of the capacitive touch panel sensors. The drive electrodes and the sense electrodes are configured to receive a second signal from an active stylus to sense active input to the capacitive touch panel at each coordinate location.