OLED Panel Ground Structure for Touch Noise and Luminance Uniformity
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Solution Overview
Problem
Flexible organic light emitting display devices face issues with voltage fluctuations and electric fields that cause touch noise and non-uniform luminance, particularly in larger sizes, due to rising low potential voltage and voltage differences between the display panel and touch panel.
Innovation Solution
A ground structure is implemented using a support member made of a metal material, with additional flexible circuit films connected to stabilize low potential voltage and suppress electric fields, ensuring a stable ground connection to the display panel and touch panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the display device is made larger in size, then the display area is increased, but the low potential voltage rises in pixels located far from the driving circuit, causing non-uniform luminance and increased power consumption
Solution Approach 1:
The ground voltage supply is segmented into multiple paths through separate flexible circuit films (first, second, and third flexible circuit films) that connect different regions of the display panel to the support member. This segmentation allows independent voltage stabilization in different areas, preventing the voltage rise that occurs in distant pixels from the single driving circuit.
Solution Approach 2:
The support member formed of metal material acts as an intermediary ground reference that receives ground connections from multiple flexible circuit films. This intermediary structure provides a stable ground potential that mediates between the driving circuit and distant pixels, ensuring uniform voltage distribution across the large display area.
2Length of stationary object
If the display panel and touch panel are disposed close to each other in a thin structure, then the device thickness is reduced, but voltage fluctuations in the thin film transistor cause touch noise on the touch panel
Solution Approach 1:
The first flexible circuit film connects the display panel to the support member, while the second flexible circuit film connects the touch panel to the same support member. This creates equipotential connections that stabilize the ground voltage for both panels, reducing voltage fluctuations that would otherwise cause touch noise in the closely disposed thin structure.
Solution Approach 2:
The support member serves as an intermediary ground structure that provides electrical connection and voltage stabilization for both the display panel and touch panel. This intermediary ground reference reduces the harmful voltage fluctuations that cause touch noise while maintaining the thin overall device structure.
3Device complexity
If a single ground connection is used for the display panel, then the structure is simple, but voltage differences between different regions of the display panel cause non-uniform luminance
Solution Approach 1:
The ground connection structure is segmented into multiple flexible circuit films (first, second, and third) that connect different regions of the display panel to the support member. This segmentation ensures that voltage is stabilized across multiple locations, preventing the voltage drops and luminance non-uniformity that would occur with a single ground connection in a large display panel.
Solution Approach 2:
Different flexible circuit films are disposed at different locations (one side and other side of the display panel) to provide localized ground connections. This local quality approach ensures that each region of the display panel has its own ground reference, maintaining luminance uniformity across the entire panel while managing the overall structure efficiently.
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 reduces touch noise and improves touch performance by stabilizing voltage and minimizing voltage differences between the display and touch panels, enhancing the operational stability and uniformity of the display.
Implementation Method 1
a voltage difference can be caused between the low potential voltage applied to the display panel and the touch panel, which can cause a touch noise in the touch panel
Implementation Method 2
a first flexible circuit film which is disposed on one side of the organic light emitting display panel and is bent toward a bottom surface of the support member
Data Source
AI summary
An organic light emitting display device can include an organic light emitting display panel, a touch panel, a support member below the organic light emitting display panel, a first flexible circuit film on one side of the organic light emitting display panel to bend toward a bottom of the support member, a second flexible circuit film on one side of the touch panel to bend toward the bottom surface of the support member, a low potential voltage line on the organic light emitting display panel, a first printed circuit board to supply a low potential voltage to the low potential voltage line, and a second printed circuit board supplied with a touch signal to the touch panel. The first and the second flexible circuit films are grounded to the support member.