Touch Panel Sensing Capacitor Segmentation for High Sensitivity
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Solution Overview
Problem
Large touch panel devices experience lower touch sensitivity due to increased equivalent capacitance of sensing lines, making it difficult to accurately detect touch events.
Innovation Solution
The implementation of a touch panel device with multiple sensing capacitors and switches, along with differential amplifiers, allows for the generation of touch readout signals through differential amplification of capacitor voltages, and a touch positioning method that involves scanning adjacent and spaced sensing elements to generate and analyze touch position signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the touch panel size is increased, then the coverage area is improved, but the touch sensitivity deteriorates due to increased equivalent capacitance of sensing lines
Solution Approach 1:
The sensing capacitor is divided into two separate capacitors (first sensing capacitor and second sensing capacitor) that are disposed at different positions on the touch panel. Each capacitor independently detects touch events in its respective region, allowing the large touch panel to maintain high touch sensitivity by treating it as multiple smaller sensing zones rather than one large sensing area with high equivalent capacitance.
2Area of stationary object
If the equivalent capacitance of sensing lines is increased due to larger panel size, then the touch panel can cover larger area, but the voltage variation for touch detection is reduced
Solution Approach 1:
By segmenting the sensing capacitor into two separate sensing capacitors positioned at different locations, each capacitor has lower individual equivalent capacitance compared to a single large sensing capacitor. This segmentation maintains sufficient voltage variation in each capacitor when touched, enabling effective touch detection across the larger panel area.
Solution Approach 2:
The patent introduces storage capacitors that are electrically connected to the sensing capacitors through switches. The storage capacitors act as intermediaries to accumulate charges transferred from the sensing capacitors, generating stable voltages for comparison. This intermediary mechanism enhances the detectability of voltage variations caused by touch events.
Solution Approach 3:
The patent employs comparators that compare the voltages of the storage capacitors with a reference voltage to generate touch readout signals. This feedback mechanism continuously monitors the voltage changes in the sensing capacitors and provides immediate detection when touch events occur, maintaining high sensitivity across the large panel area.
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
This configuration enhances touch sensitivity by effectively detecting touch events, including multi-point touches, with improved accuracy and sensitivity across larger touch panel sizes.
Implementation Method 1
Each sensing capacitor 120 can be an equivalent capacitor of one corresponding sensing line 110. When the touch panel 101 is touched, the capacitance of a sensing capacitor 120 corresponding to touched position increases accordingly
Implementation Method 2
The differential amplifier, electrically connected to the first storage capacitor and the second storage capacitor, is employed to generate a touch readout signal through performing a differential amplification operation on the first and second voltages
Data Source
AI summary
A touch panel device having high touch sensitivity includes sensing capacitors, switches, storage capacitors, a differential amplifier and a signal processing unit. During a sense period, the switches are periodically turned on alternately for periodically transferring the charges of the sensing capacitors to the storage capacitors. The differential amplifier is put in use for amplifying the voltage difference of two corresponding storage capacitors for generating a touch readout signal. The signal processing unit performs an OR operation on two touch readout signals generated during different sense periods based on different sensing capacitor combinations regarding same panel touch position for providing a touch position signal.