Touch Sensing System Adjusting Driving Signal Voltage by RC Delay
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Solution Overview
Problem
Large-sized capacitive touch screens experience non-uniform charge characteristics due to varying RC delays, leading to reduced touch sensitivity and signal-to-noise ratio, as the size of the touch screen increases, resulting in decreased touch report rates and increased latency in coordinate recognition.
Innovation Solution
A touch sensing system that applies customized driving signals with varying widths, voltages, or numbers based on the RC delay at different positions on the touch screen to uniformize charge characteristics, including a pre-charging period, high potential holding period, discharge acceleration period, and reference potential period, to ensure consistent charging and discharging of touch sensors across the screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of the touch screen increases, then the touch screen can provide larger display area and better durability, but the RC delay increases causing non-uniform charge characteristics and reduced touch sensitivity
Solution Approach 1:
The patent applies different driving signal parameters (voltage, width, or number of signals) to different regions of the touch screen based on their specific RC delay characteristics. The touch screen is divided into multiple regions, each receiving customized driving signals to compensate for local variations in RC delay, thereby achieving uniform charge characteristics across the entire large-sized screen.
Solution Approach 2:
The patent modifies driving signal parameters (voltage level, pulse width, or number of signals) as a function of the RC delay at different positions. By dynamically adjusting these parameters based on the measured or predetermined RC delay characteristics of each region, the system compensates for the increased RC delay in large-sized touch screens and maintains uniform charging behavior.
2Area of stationary object
If the RC delay increases due to larger touch screen size, then the touch screen area is increased, but the discharge time of touch sensors increases reducing touch report rate
Solution Approach 1:
The patent implements region-specific driving signal customization where each region receives tailored signals based on its RC delay characteristics. This local optimization ensures that even distant regions with higher RC delay achieve proper charging and discharging timing, maintaining high touch report rates across the entire large screen.
Solution Approach 2:
The patent applies preliminary driving signals before the main sensing period to pre-charge the touch sensors in regions with high RC delay. This preliminary action ensures that sensors are fully charged before the sensing period begins, and subsequently can be rapidly discharged, maintaining high touch report rates despite the larger screen size.
3Area of stationary object
If the driving signal is applied to touch sensors far from the ROIC, then the touch screen area is expanded, but the amount of charges charged to touch sensors decreases due to RC delay
Solution Approach 1:
The patent customizes driving signal parameters for different regions based on their distance from the ROIC and resulting RC delay. Regions farther from the ROIC receive signals with adjusted voltage, width, or number of pulses to compensate for the increased RC delay, ensuring that sufficient charges are delivered to touch sensors regardless of their position on the expanded screen.
Solution Approach 2:
The patent changes driving signal parameters (increasing voltage, extending pulse width, or repeating signals multiple times) as a function of the RC delay at different positions. This parameter adjustment ensures that touch sensors far from the ROIC receive adequate charging to achieve the same charge level as sensors near the ROIC, maintaining uniform performance across the entire screen.
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 approach enhances the signal-to-noise ratio, reduces charge and discharge times, and increases touch sensitivity by uniformly supplying charges and rapidly discharging touch sensors, thereby improving the touch report rate and user feedback.
Implementation Method 1
A capacitive touch sensing system includes a capacitive touch screen... Each of the touch sensors has a capacitance when viewed through an equivalent circuit
Implementation Method 2
As the size of the touch screen increases, the length of lines used in the touch screen lengthens. Hence, a resistance and a capacitance of the touch screen increase, and an RC delay of a driving signal applied to the touch screen increases
Data Source
AI summary
A touch sensing system and a method for driving the same are disclosed. The touch sensing system includes a touch screen including touch sensors and a touch sensing circuit applying a driving signal to the touch sensors. The touch sensing circuit applies at least one first driving signal to a first position of the touch screen and applies at least one second driving signal to a second position of the touch screen. When RC delay of the first position is less than RC delay of the second position, at least one of a width and a voltage of the second driving signal is greater than the first driving signal, or the number of second driving signals is more than the number of first driving signals.