OLED Display Common Voltage Wiring for Luminance Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large-sized organic light emitting diode (OLED) displays face challenges in minimizing voltage drop and achieving uniform luminance due to bonding defects and increased dead space caused by flexible printed circuits used for common voltage supply.
Innovation Solution
The implementation of a display device structure that includes a substrate with a common voltage line, auxiliary wiring connected to the common voltage line, and a touch panel, where the auxiliary wiring is disposed on a thin film encapsulation layer or an insulating layer, and optionally on the same layer as the touch wiring, to minimize voltage drop and improve luminance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flexible printed circuit (FPC) is used to supply common voltage to large-sized OLED display, then common voltage can be supplied to entire region, but voltage drop increases and bonding defect rate increases
Solution Approach 1:
The common voltage line is divided into multiple segments (first common voltage line and second common voltage line) disposed in different regions of the substrate. This segmentation allows the common voltage to be distributed more efficiently across the large-sized display, reducing voltage drop in any single region while maintaining reliable voltage supply to the entire display area.
Solution Approach 2:
The auxiliary wiring is disposed on the thin film encapsulation layer (a different dimensional plane from the substrate), creating a three-dimensional wiring structure. This allows the auxiliary wiring to connect the first and second common voltage lines without interfering with the planar layout, enabling effective voltage distribution across large areas while minimizing voltage drop.
2Reliability
If flexible printed circuit (FPC) is bonded on two sides of OLED display, then common voltage can be supplied, but bonding defect rate increases and dead space increases
Solution Approach 1:
The auxiliary wiring and touch wiring are merged into the same layer structure, both disposed on the thin film encapsulation layer. This integration eliminates the need for separate bonding structures for auxiliary wiring, reducing dead space and bonding defect rates while maintaining reliable common voltage supply to the entire display area.
3Reliability
If common voltage line is extended to cover entire display region, then uniform voltage supply is achieved, but voltage drop increases
Solution Approach 1:
Different wiring structures are applied to different regions of the display. The first common voltage line is disposed in the first region and the second common voltage line in the second region, with auxiliary wiring connecting them. This localized approach optimizes voltage distribution in each region while maintaining overall voltage uniformity across the entire display, minimizing voltage drop through strategic placement rather than uniform extension.
Data Source
AI summary
A display device includes: a substrate: a first electrode and a second electrode disposed on the substrate and facing each other; an emission layer disposed between the first electrode and the second electrode; a common voltage line disposed on the substrate and connected to the second electrode to transmit a common voltage; a thin film encapsulation layer covering the second electrode; auxiliary wiring disposed on the thin film encapsulation layer and connected to the common voltage line; a covering layer covering the auxiliary wiring; and a touch panel disposed on the covering layer. Thus, a voltage drop of the common voltage ELVSS may be minimized, and the luminance uniformity may be improved.