Touch Panel Sensor Resistor Section for Accurate Touch Detection
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Solution Overview
Problem
Touch panels with high parasitic capacitance in sensor lines require significant time to charge, leading to incorrect detection of touch events due to the pull-up resistor and line selecting circuit, causing the execution of internal programs even when no touch event occurs.
Innovation Solution
The touch panel design includes sensor lines with sensor switches and a sensor resistor section where the sensor resistors are connected to the input terminals of the line selecting unit, preventing voltage changes from selecting transistors and ensuring accurate detection of touch events by applying driving DC voltage directly to the output terminals of the sensor switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor line is formed to have high parasitic capacitance to store charge, then the sensor line can maintain voltage levels, but a large amount of time is required to charge the output terminal of the sensor switch, causing the sensor line to not be charged with driving DC voltage during turn-on time
Solution Approach 1:
The patent applies preliminary action by pre-charging the sensor line with driving DC voltage through the sensor resistor section before the sensor switch needs to output signals. This ensures that the sensor line is already charged and ready to maintain proper voltage levels without requiring additional charging time when the switch activates, thus resolving the time delay issue while maintaining the necessary charge storage capability.
Solution Approach 2:
The sensor resistor section acts as an intermediary element between the driving DC voltage source and the sensor line. It provides a dedicated charging path that is independent of the sensor switch, allowing the sensor line to be charged through this intermediary resistor without being affected by the switch's turn-on time constraints, thereby resolving the contradiction between charge storage and charging time.
2Ease of manufacture
If the pull-up resistor and line selecting circuit are used to charge the sensor line, then the circuit can operate with standard components, but these components prevent the output terminal of the sensor switch from being charged with driving DC voltage
Solution Approach 1:
The patent segments the charging function from the signal output function by introducing a separate sensor resistor section dedicated to charging the sensor line with driving DC voltage. This segmentation allows the pull-up resistor and line selecting circuit to maintain their signal routing functions while the sensor resistor section independently handles the charging function, ensuring reliable voltage charging without interference from other circuit components.
Solution Approach 2:
The sensor resistor section serves as an intermediary charging path that bypasses the limitations of the pull-up resistor and line selecting circuit. It provides a direct route for driving DC voltage to charge the sensor line, ensuring reliable voltage charging while allowing the existing pull-up resistor and line selecting circuit to continue their intended functions without modification.
3Use of energy by moving object
If the sensor line is not properly charged with driving DC voltage, then the circuit avoids excessive power consumption, but the touch panel may execute internal programs of touch events even when no touch event occurs
Solution Approach 1:
The patent applies preliminary action by pre-charging the sensor line with driving DC voltage through the sensor resistor section before touch detection begins. This ensures that the sensor line maintains proper voltage levels throughout operation, enabling accurate touch event detection while avoiding false positives. The preliminary charging establishes a stable baseline that consumes minimal power while ensuring detection reliability.
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 design enhances the ability to accurately detect touch events, preventing false execution of internal programs and improving the overall performance of the touch panel by ensuring that the sensor lines and switches are charged correctly.
Implementation Method 1
The sensor line is formed on the touch panel to have a high parasitic capacitance so that the sensor line stores some quantity of charge.
Implementation Method 2
An input terminal of the operational amplifier is electrically connected to a pull-up resistor so that the operational amplifier compares the sensing signals with a reference voltage.
Data Source
AI summary
In a touch panel and a display apparatus having the touch panel, the touch panel includes a plurality of sensor lines, a plurality of sensor switches, a line selecting unit and a sensor resistor section. The sensor switches are electrically connected to the sensor lines, respectively, and apply sensing signals to the sensor lines, respectively, when a touch event occurs. The line selecting unit is electrically connected to end portions of the sensor lines and sequentially outputs the sensing signals transferred through the sensor lines. The sensor resistor section includes a first end electrically connected to the sensor lines, respectively, and a second end opposite to the first end. The second end receives a driving direct current (DC) voltage. Therefore, the touch panel may have an improved ability to detect touch events.