Capacitive Pen State Detection for Shape-Dependent Signal Variation
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Solution Overview
Problem
Existing pen state detection systems face accuracy issues due to changes in the outer shape of electronic pens or equipment, affecting the geometric relation between pen-side and sensor electrodes, which alters signal distribution patterns.
Innovation Solution
A pen state detection circuit and method that adjusts the input-output model based on changes in the outer shape of the electronic pen or equipment, using a parameter supply device to set model parameters that account for variations in pen type, equipment type, touch sensor type, and user interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed input-output model is used for pen state detection, then the system structure is simple and easy to implement, but the detection accuracy decreases when the outer shape of the pen or equipment changes
Solution Approach 1:
The patent implements a dynamic input-output model that can be switched between multiple models based on detected conditions. The system changes the model parameters according to the geometric relationship between the pen and sensor, allowing the detection system to adapt to different pen orientations and distances, thereby maintaining high detection accuracy without requiring a single overly complex fixed model
Solution Approach 2:
The patent changes parameters of the input-output model based on detected geometric relationships. When the pen angle or distance changes, the system adjusts model parameters such as capacitance values and geometric factors to match the current configuration, enabling accurate detection across varying conditions while keeping the base model structure relatively simple
2Reliability
If the input-output model is adjusted to account for outer shape changes, then the detection accuracy is maintained, but the system complexity increases
Solution Approach 1:
The patent employs feedback mechanisms where the system continuously monitors the geometric relationship between the pen and sensor, compares detected values with expected ranges, and automatically adjusts the input-output model accordingly. This feedback loop ensures consistent detection accuracy across different conditions while automating the model adjustment process to reduce manual intervention complexity
Solution Approach 2:
The patent performs preliminary detection of geometric relationships and pre-selects appropriate model configurations before actual pen state detection. By anticipating needed model adjustments based on initial geometric assessments, the system maintains accuracy without requiring complex real-time model restructuring during the detection process itself
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
Maintains high accuracy in detecting pen states despite changes in shape or condition, ensuring precise position and orientation estimation of electronic pens.
Implementation Method 1
signal distribution indicating a change in capacitance associated with approach of a pen-side electrode included in an electronic pen
Data Source
AI summary
A pen state detection circuit is incorporated in electronic equipment having a touch sensor of a capacitive system made of planarly disposed multiple sensor electrodes. The pen state detection circuit is configured to perform acquiring, from the touch sensor, signal distribution indicating a change in capacitance associated with approach of a pen-side electrode included in an electronic pen, and estimating a state of the electronic pen according to an input-output model. In the input-output model features relating to the acquired signal distribution are input and a state quantity of the electronic pen is output. The pen state detection circuit is configured to be capable of setting an input-output model that is different depending on a change in an outer shape of the electronic pen or the electronic equipment.