Touch Panel LCD Device Common Line Load-Free Driving Signal
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Solution Overview
Problem
Conventional touch panel LCD devices face limitations in achieving thin films due to increased thickness, reduced light transmittance, and high manufacturing costs, along with non-uniformity in touch data due to parasitic capacitance between the black matrix layer and common lines, which affects touch sensing performance.
Innovation Solution
A touch panel LCD device with a self-capacitive type in-cell structure where common lines are arranged in a non-display area and connected to a flexible printed circuit board (FPCB) to apply a load-free driving (LFD) signal during the touch sensing period, preventing parasitic capacitance and ensuring uniform touch data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a touch panel is additionally stacked on the LCD device, then touch sensing function is achieved, but device thickness increases and light transmittance efficiency is reduced
Solution Approach 1:
The patent merges the touch panel and LCD device into a single integrated structure. The touch sensor electrodes are formed within the LCD device structure itself, specifically using the common electrode and black matrix layer as part of the touch sensing system, eliminating the need for a separate stacked touch panel while maintaining both display and touch sensing functions.
Solution Approach 2:
The patent makes existing LCD components serve multiple functions. The common electrode and black matrix layer are utilized not only for their original LCD functions but also as part of the touch sensing system, enabling the device to perform both display and touch sensing operations through a single integrated structure.
2Adaptability or versatility
If a low resistance ITO film is used for touch sensing, then touch sensing capability is provided, but charges leak externally through the film deteriorating touch sensing performance
Solution Approach 1:
The patent applies different resistance characteristics to different regions and components. The touch sensor electrode uses high resistance material to prevent charge leakage, while other conductive components maintain their original resistance characteristics. This localized differentiation of electrical properties allows the system to achieve both touch sensing capability and charge retention.
Solution Approach 2:
The patent changes the resistance parameter of the touch sensor electrode material from low resistance (ITO) to high resistance material. This parameter change prevents charge leakage through the electrode while maintaining the electrode's ability to detect touch input, thereby improving touch sensing performance.
3Ease of manufacture
If common lines are connected to FPCB without LFD signal, then parasitic capacitance forms between black matrix layer and common lines, causing non-uniformity in touch data
Solution Approach 1:
The patent applies the load-free driving (LFD) signal to the common lines before and during the touch sensing period as a preliminary action. This pre-conditioning of the common lines prevents parasitic capacitance formation between the black matrix layer and common lines, ensuring uniform touch data acquisition across the display.
Solution Approach 2:
The patent implements a feedback mechanism where the LFD signal is continuously applied to the common lines during the touch sensing period based on the detection of touch input. This feedback control maintains optimal electrical conditions for accurate touch sensing by preventing parasitic capacitance effects.
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
The solution effectively prevents non-uniformity of raw touch data by eliminating parasitic capacitance between the black matrix layer and common lines, enhancing touch sensing performance and maintaining normal operation of touch electrodes.
Implementation Method 1
a Y1 film having a high resistance (a few tens of MΩ) is formed, instead of the ITO film 5, in order to improve touch sensing performance
Implementation Method 2
Although not illustrated in the figure, a liquid crystal layer is formed between the TFT array substrate 1 and the color filter array substrate 2
Implementation Method 3
An upper polarizing plate 7 and a lower polarizing plate 6 are formed on the top surface of the ITO film 5 and the bottom surface of the TFT array substrate 1, respectively
Data Source
AI summary
Disclosed are a touch panel LCD device capable of improving touch sensing performance by preventing non-uniformity of raw touch data of left and right sides and a method of driving the same. In the touch panel LCD device, a plurality of common lines arranged in a non-display area of a panel and configured to check characteristics of the panel is connected to a load free driving (LFD) signal line by a flexible printed circuit board (FPCB) when the common lines are attached to the FPCB.