Charge Distribution Touch Sensing Circuit Design
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Solution Overview
Problem
Conventional capacitive touch panels require multiple high precision capacitors and complex calculations to accurately determine touch sensing regions, leading to increased complexity and cost.
Innovation Solution
A touch sensing method and apparatus using a charge distribution approach with interlaced axial electrodes, switch units, and a processing unit to inject and distribute charges, allowing for the acquisition of an equivalent voltage to determine object proximity without the need for additional high precision capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple high precision capacitors are used to measure sensing capacitors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the measurement function from multiple high precision capacitors and implements it through a single capacitor combined with charge redistribution methodology. The sensing capacitor Cs is charged to voltage V1, then redistributed with reference capacitor Cr to generate equivalent voltage Vout, eliminating the need for multiple precision capacitors while maintaining measurement capability.
Solution Approach 2:
The patent changes the measurement approach from direct capacitance comparison to equivalent voltage measurement through charge redistribution. By transforming the physical quantity being measured from capacitance ratio to voltage level, the system achieves the same measurement precision with simpler components.
2Measurement precision
If multiple high precision capacitors with different capacitances are used, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the measurement function from multiple precision capacitors and implements it through a single capacitor with charge redistribution methodology, reducing component quantity and manufacturing cost.
Solution Approach 2:
The patent replaces expensive high precision capacitors with standard precision capacitors that are cheaper and more readily available, achieving the same measurement function through intelligent circuit design rather than relying on expensive components.
3Measurement precision
If several times of integrations and complicated calculations are performed, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex computational processing with direct electrical measurement. Instead of performing multiple integrations and calculations on capacitance values, the system directly measures the equivalent voltage Vout which inherently encodes the touch position information, simplifying the processing chain.
Solution Approach 2:
The patent transforms the measurement parameter from capacitance (requiring complex calculations) to voltage (directly measurable), eliminating the need for complex integration and calculation operations while maintaining measurement precision.
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
Simplifies the circuit design, reduces costs, and eliminates the dependency on absolute capacitance values, enabling precise touch sensing without the need for multiple high precision capacitors, thus enhancing operational efficiency and reducing complexity.
Implementation Method 1
a touch sensing method and a touch sensing apparatus of charge distribution type
Implementation Method 2
an equivalent voltage is acquired after the charges are distributed at an equilibrium state
Data Source
AI summary
A touch sensing method of charge distribution type is disclosed. Firstly, charges in a panel are removed. Next, a scanning signal is provided to scan a plurality of sensing regions of the panel. Subsequently, the panel is set in a first switching mode for charging the panel with the scanning signal. Thereafter, the panel is set in a second switching mode for modifying a distribution of charges injected into the panel. Next, an equivalent voltage is acquired after the charges are distributed at an equilibrium state. Furthermore, a touch sensing apparatus with charge distribution type is provided herein.