Touch Detection Using Gate Line Waveforms in Liquid Crystal Displays
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Solution Overview
Problem
Traditional touch screen technologies are limited by high costs, low contrast, increased module thickness, and inability to perform multi-touch detection, restricting their applications.
Innovation Solution
A display apparatus with touch control units, including switching elements, sensing capacitance, and liquid crystal capacitance, coupled to gate and readout lines, allowing for multi-touch detection by determining the position, amount, and timing of touch events based on waveforms on the readout line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ITO module is used for touch screen detection, then touch detection function is achieved, but cost increases and module thickness increases
Solution Approach 1:
The patent merges the touch detection function with the existing liquid crystal display structure by integrating sensing capacitance into the pixel units. The sensing capacitance is formed using existing display components (gate lines, liquid crystal layer, common electrode) rather than adding a separate ITO module, thereby eliminating the need for additional thickness while maintaining touch detection capability
Solution Approach 2:
The patent makes the liquid crystal display panel multi-functional by enabling it to perform both display and touch detection functions simultaneously. The same structural components (gate lines, liquid crystal layer, electrodes) serve dual purposes: driving the display and detecting touch inputs, thus eliminating the need for separate dedicated touch detection modules
2Reliability
If traditional ITO module is used for touch screen detection, then touch detection function is achieved, but cost increases
Solution Approach 1:
The patent combines touch detection functionality with the existing display manufacturing process. By using the same gate lines, liquid crystal layer, and electrode structures for both display and touch detection, the patent eliminates the need for separate ITO module production and assembly, thereby reducing manufacturing costs
Solution Approach 2:
The display panel structure serves itself by using its own components (gate lines, liquid crystal capacitance, common electrode) to perform touch detection. The sensing capacitance is formed using existing display components, eliminating the need for additional expensive materials like ITO and reducing overall manufacturing costs
3Object-affected harmful factors
If press-type touch screen with common voltage detection is used, then immunity to ambient light is achieved, but multi-touch detection capability is lost
Solution Approach 1:
The patent divides the touch detection into multiple independently controllable pixel units, each with its own sensing capacitance connected to gate lines and readout lines. This segmentation allows multiple touch points to be detected simultaneously by monitoring different gate line signals, enabling multi-touch detection while maintaining the press-type detection method that is immune to ambient light
Solution Approach 2:
The patent implements a feedback mechanism where the control unit applies common voltage swings to gate lines and reads the resulting signals through readout lines. By analyzing the timing sequence and waveform changes in the feedback signals, the system can determine multiple touch positions simultaneously while maintaining immunity to ambient light interference through the press-type detection principle
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
Enables multi-touch detection, enhancing application capabilities while reducing costs and module thickness, and improving user interface intuitiveness.
Implementation Method 1
each of the touch control units further includes a sensing capacitance and a liquid crystal capacitance electrically coupled with the sensing capacitance in series
Data Source
AI summary
An exemplary display apparatus includes a plurality of pixel units, a plurality of gate lines, a readout line and a plurality of touch control units. The gate lines are for deciding whether to enable the pixel units. Each of the touch control units is electrically coupled to the readout line and a corresponding one of the gate lines and includes a switching element. When one of the touch control units is touched, the switching element of the touched touch control unit is turned on, and thereby a waveform on the gate line corresponding to the touched touch control unit is coupled to the readout line and a position of the touched touch control unit is determined according to a timing sequence of a waveform on the readout line. The present invention also provides a touch detection method adapted to be implemented on the above-mentioned display apparatus.