Display Device Position Input Function Potential Retention
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Solution Overview
Problem
Conventional display devices with position input functions face challenges in maintaining display integrity due to difficulties in retaining the pixel electrode at the required potential for image display, leading to potential voltage drops and display integrity issues when using time-divisional signal supply methods.
Innovation Solution
The implementation of a display device configuration with a pixel electrode, a common electrode overlapping via an insulating film, and position detection electrodes that form electrostatic capacitance, along with a switching element connecting the position detection electrode to a drive signal line, allows for improved potential retention and reduced voltage drops by supplying signals in a time-divisional manner, ensuring the touch electrode reaches a predetermined reference potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If time-divisional signal supply method is used for position detection, then position input function can be implemented, but display integrity deteriorates due to potential differences between touch electrodes
Solution Approach 1:
The patent applies equipotentiality by connecting all touch electrodes to a common electrode that is maintained at a fixed reference potential through a dedicated common signal line. This ensures that during position detection operations, all touch electrodes remain at the same potential, eliminating potential differences between them while still allowing time-divisional signal supply for position input functionality.
Solution Approach 2:
The patent segments the signal supply system into separate dedicated lines: one for position detection signals and another for maintaining reference potential. This segmentation allows independent control of detection operations while maintaining stable reference potentials, resolving the contradiction between enabling position input and maintaining display integrity.
2Device complexity
If common signal line resistance is high, then device complexity is reduced, but voltage drop increases causing touch electrodes to fail reaching reference potential
Solution Approach 1:
The patent ensures equipotential conditions by designing the common signal line to supply reference potential to all touch electrodes simultaneously, compensating for line resistance effects. The common electrode acts as a potential equalizer, ensuring that even with high line resistance, all touch electrodes reach the required reference potential for reliable operation.
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 enhances display integrity by preventing potential differences between touch electrodes and maintaining the common electrode at a reference potential during image display, thereby improving the overall display quality.
Implementation Method 1
two or more position detection electrodes obtained by dividing the common electrode, the two or more position detection electrodes forming an electrostatic capacitance between a positon input body performing position input and the position detection electrodes and detecting a position of the position input performed by the position input body
Implementation Method 2
a switching element connected to the first line, the second line and the position detection electrode, the switching element connecting the second line to the position detection electrode when driven by the drive signal transmitted to the first line
Data Source
AI summary
A display device having position input function includes: a pixel electrode; a common electrode at least partially overlapping with the pixel electrode via an insulating film; position detection electrodes obtained by dividing the common electrode, forming capacitance between a positon input body performing position input and the position detection electrodes, and detecting an input position by the position input body; a position detection line supplying a position detection signal and a common signal for bringing the position detection electrode into a reference potential in a time-divisional manner; a first line through which a drive signal is transmitted; a second line crossing the first line; and a switching element connected to the first line, the second line and the position detection electrode, the switching element connecting the second line to the position detection electrode when driven by the drive signal transmitted to the first line.