Segmented Common Electrodes for LCD Touch Panels
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Solution Overview
Problem
In liquid crystal display devices with touch panels, using the common electrode as a drive electrode results in high power consumption due to large capacitance and requires offset adjustment for detection sensitivity, making it difficult to enhance detection sensitivity.
Innovation Solution
The liquid crystal display device incorporates pixel electrodes, common electrodes, and detection electrodes, where the common electrodes have a first electrode for detection potential and a second electrode with a different potential, with a narrower cross portion and overlapping areas optimized to reduce transient current and power consumption, while maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the common electrode is used as the drive electrode of the touch panel, then the device structure is simplified and manufacturing is easier, but the power consumption increases due to large capacitance and transient current
Solution Approach 1:
The common electrode is segmented into a first electrode and a second electrode that are electrically disconnected from each other. The first electrode serves as the drive electrode for touch panel detection, while the second electrode serves as the common electrode for liquid crystal display. This segmentation reduces the capacitance and transient current associated with using the entire common electrode as the drive electrode, thereby reducing power consumption while maintaining manufacturing simplicity.
2Device complexity
If the common electrode is used as the drive electrode, then the electrode structure is simplified, but the detection sensitivity decreases due to large offset current requiring adjustment
Solution Approach 1:
By segmenting the common electrode into first and second electrodes, the patent reduces the overlap area between the drive electrode and detection electrode. This reduction minimizes the offset current generated during detection, thereby improving detection sensitivity without requiring complex offset adjustment mechanisms.
Solution Approach 2:
The first electrode is designed with a specific shape that has a narrower width in the region overlapping with the detection electrode compared to other regions. This local quality optimization reduces the capacitance and transient current in the critical detection area, thereby enhancing detection sensitivity while maintaining the overall simplicity of the electrode structure.
3Use of energy by moving object
If the cross portion area of drive electrode and detection electrode is reduced, then the transient current and power consumption are reduced, but the image quality may be compromised
Solution Approach 1:
The first electrode is designed with non-uniform width, being narrower in the region overlapping with the detection electrode and wider in other regions. This local quality optimization allows the electrode to maintain sufficient area for image display quality while reducing the cross portion area with the detection electrode to minimize transient current and power consumption.
Solution Approach 2:
The patent applies different potentials to the first and second electrodes dynamically during operation. The first electrode receives the detection potential for touch panel operation, while the second electrode receives the common electrode potential for liquid crystal display. This dynamic potential application allows the system to optimize performance for different functions without compromising image quality.
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 suppresses power consumption and enhances detection sensitivity by reducing transient current and offset current, allowing for more precise touch position detection without compromising image quality.
Implementation Method 1
a liquid crystal layer having a liquid crystal composition whose orientation is changed according to an electric field developed by the pixel electrodes and the common electrodes
Implementation Method 2
a capacitive coupling type that detects a change in capacitance
Data Source
AI summary
A liquid crystal display device with a touch panel includes: pixel electrodes which is applied a electrical potential corresponding to a gradation value in respective pixels; common electrodes that are a plurality of electrodes which extend in one direction; a liquid crystal layer having a liquid crystal composition whose orientation is changed according to an electric field developed by the pixel electrodes and the common electrodes; and detection electrodes that are a plurality of electrodes which extend in another direction different from the one direction, and detect a touch position on the panel. The common electrodes include a first electrode which is applied a detection potential for detecting the touch position on the panel, and a second electrode to which a potential different from the detection potential is applied during a period in which the detection potential is applied.