Embedded Touch Screen With Shared Electrodes For Accurate Detection
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Solution Overview
Problem
Conventional embedded touch screens face challenges in achieving accurate coordinate detection without reducing the pixel aperture ratio and increasing the complexity of the detection circuit, particularly in small-sized or high-resolution displays.
Innovation Solution
The design incorporates a configuration with excitation and detection electrodes that include pixel, common, and video signal shielding electrodes, arranged in a manner that allows for simultaneous signal detection across multiple directions, utilizing a simpler detection circuit without significantly altering the existing liquid crystal display device configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a TFT different from a TFT for driving liquid crystal is provided in the pixel for embedded touch screen function, then coordinate detection capability is achieved, but the pixel aperture ratio reduces
Solution Approach 1:
The invention makes the liquid crystal display device's pixel structure serve dual functions: both liquid crystal driving and touch detection. By using the pixel electrode as excitation electrode and the common electrode as detection electrode, the same structural elements perform multiple functions, eliminating the need for separate dedicated touch detection TFTs and maintaining high aperture ratio.
Solution Approach 2:
The invention merges the liquid crystal driving function and touch detection function into a single integrated system. The pixel structure, originally designed solely for liquid crystal driving, is combined with capacitive touch detection functionality by utilizing the inherent electrodes (pixel electrode and common electrode) for both purposes simultaneously.
2Measurement precision
If the common electrode is divided into blocks for mutual capacitive coupling to improve coordinate detection accuracy, then detection accuracy increases, but the circuit scale of the detection circuit increases
Solution Approach 1:
The invention uses the liquid crystal display device's existing scanning circuit and video signal lines for touch detection purposes. The scanning signal lines are used to apply alternating signals to pixel electrodes, and the video signal lines are used to read detection signals from the common electrode, eliminating the need for separate dedicated detection circuits and amplifiers for each electrode block.
Solution Approach 2:
The invention makes the liquid crystal display device's own circuits serve the touch detection function. The scanning circuit that originally drives the liquid crystal display now also applies excitation signals for touch detection, and the video signal lines that originally display images now also carry detection signals, allowing the system to detect touches using its existing infrastructure without additional complex circuitry.
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 enables accurate coordinate detection with a simpler detection circuit, reducing the circuit size and detection time, while maintaining high sensitivity and not affecting the image display, even in small-sized or high-resolution screens.
Implementation Method 1
an application circuit for applying an alternating signal to a plurality of excitation electrodes each arranged along one of the first direction and the second direction; a detection circuit for detecting a signal excited on a plurality of detection electrodes each arranged adjacent to each of the plurality of excitation electrodes
Data Source
AI summary
Provided is an embedded touch screen, including: a first substrate; a second substrate including: scanning signal lines extending in a first direction; video signal lines extending in a second direction; a plurality of pixels each including a pixel electrode connected to corresponding one of the video signal lines via a switching element connected to corresponding one of the scanning signal lines; and a common electrode; a liquid crystal layer; an application circuit for applying an alternating signal to a plurality of excitation electrodes; a detection circuit for detecting a signal excited on a plurality of detection electrodes each arranged adjacent to each of the plurality of excitation electrodes; and a scanning circuit for scanning at least one of each of the plurality of excitation electrodes and each of the plurality of detection electrodes at least in the second direction.