Optical Touch Panel Pixel Matrix for Crosstalk Reduction
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Solution Overview
Problem
Conventional liquid crystal displays with optical detecting means face challenges in high-speed scanning due to wired gate lines, leading to crosstalk between displayed images and captured optical images, especially in dot-type input systems like touch panels.
Innovation Solution
The image display device incorporates a matrix arrangement of pixels with display brightness modulation and optical detecting means, featuring optical sense elements, signal electric-carrier resetting components, and output impedance modulation, with the output impedance modulating means connected in series to enable efficient optical detection without interfering with image display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gate line is wired all over the display screen to scan the optical signal electric-carrier capacitor, then the optical image can be captured, but the scanning speed is limited and crosstalk occurs between the displayed image and the optical image
Solution Approach 1:
The patent segments the optical detection function from the display function by providing separate optical detecting means for each pixel. Each optical detecting means includes an optical detection TFT and capacitor that can be independently controlled, allowing simultaneous display and optical capture without requiring full gate line scanning. This segmentation enables faster optical detection while maintaining display quality.
Solution Approach 2:
The patent implements preliminary action by pre-configuring the optical detecting means within each pixel structure before operation. The optical detection TFTs and capacitors are built into the pixel structure in advance, allowing immediate optical detection when needed without requiring sequential gate line scanning across the entire display. This preliminary configuration enables rapid optical image capture.
2Measurement precision
If the gate line scans throughout the display screen to capture one frame of optical image, then the optical detection can be completed, but the time required is equivalent to one frame period causing crosstalk
Solution Approach 1:
The patent divides the optical detection task into independent pixel-level operations. Each pixel's optical detecting means can detect and store optical signals independently using its own capacitor, eliminating the need for sequential scanning across all pixels. This segmentation reduces detection time from one full frame period to a much shorter duration while maintaining detection accuracy.
Solution Approach 2:
Each pixel's optical detecting means serves itself by containing all necessary components (optical detection TFT, capacitor) within the pixel structure. The optical signal electric-carrier capacitor at each pixel stores the detected signal locally without requiring external scanning or reading operations, enabling rapid independent detection across all pixels simultaneously.
3Device complexity
If conventional optical detecting means are used with wired gate lines, then the structure is simple, but crosstalk occurs between display and input signals
Solution Approach 1:
The patent segments the detection function into independent pixel units with dedicated optical detecting means. Each pixel contains its own optical detection TFT and capacitor, creating electrically isolated detection channels that prevent crosstalk between display and input signals. This segmentation maintains structural simplicity while significantly improving signal separation reliability.
Solution Approach 2:
The patent introduces the optical signal electric-carrier capacitor as an intermediary element between the optical detection TFT and the external reading circuitry. This capacitor buffers and stores the detected optical signal, isolating it from the display circuitry and preventing crosstalk. The intermediary structure maintains simplicity while ensuring reliable signal separation.
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 allows for rapid optical detection within a single frame period, minimizing crosstalk and enabling accurate touch input detection without disrupting the displayed image, thus improving the performance of optical touch panels.
Implementation Method 1
optical sense means for converting incident lights into signal electric-carriers
Data Source
AI summary
The invention is to provided an integrated, optical touch panel type image display device free from crosstalk with displayed images. The image display device according to the invention comprises a plurality of pixels having display brightness modulation means controlled with display signals, a display unit in which the plurality of pixels are arrayed, and a plurality of optical detecting means provided within the display unit wherein each of the optical detecting means comprises an optical detection diode for converting incident lights into signal electric-carriers, signal electric-carrier resetting means for resetting the signal electric-carriers, and output impedance modulating means for detecting the signal electric-carriers and modulating output impedances. The output impedance modulating means in the optical detecting elements are connected, in series between each other, to a Y output line and an X output line.