OLED Cathode Groove Contact Layout for Narrow-Bezel Displays
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Solution Overview
Problem
Conventional display devices face challenges in aligning substrates and deposition masks, leading to misalignment and increased frame size due to the need for a contact electrode on the outer periphery of the light-emitting pixel area to ensure low contact resistance, which hinders the narrowing of the display panel frame.
Innovation Solution
A display device configuration featuring a groove formed along the pixel arrangement direction in the insulating film, with a contact electrode at the bottom of the groove to electrically connect the cathode electrode, allowing for reduced frame size by eliminating the need for a contact electrode on the outer periphery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact electrode is provided on the outer periphery of the light-emitting pixel area to ensure low contact resistance, then the electrical connection reliability is improved, but the frame size increases
Solution Approach 1:
The contact electrode is moved from the outer periphery (2D plane) to the bottom of a groove (vertical dimension/Z-axis). This dimensional transition allows the contact electrode to be positioned within the pixel area rather than on its boundary, reducing the frame size while maintaining electrical connection reliability through the groove structure that ensures stable contact.
Solution Approach 2:
The contact electrode is nested within the groove structure formed in the insulating film. This nesting approach allows the contact electrode to be embedded within the existing pixel area structure rather than occupying additional peripheral space, thereby reducing frame size while maintaining reliable electrical connection through the enclosed groove configuration.
2Reliability
If the contact electrode size is increased to account for alignment accuracy and substrate warpage, then the electrical connection stability is improved, but the manufacturing precision requirement worsens
Solution Approach 1:
By positioning the contact electrode in the vertical dimension (bottom of groove) rather than expanding it horizontally to compensate for alignment issues, the need for large tolerance margins is reduced. The groove structure provides mechanical constraint that maintains alignment precision without requiring excessive contact electrode area.
3Reliability
If the contact electrode is positioned on the outer periphery to ensure sufficient contact area, then the contact resistance is reduced, but the device complexity increases
Solution Approach 1:
The contact electrode is nested within the groove structure, which provides the necessary contact area and low contact resistance without requiring the electrode to extend to the periphery. This nested configuration simplifies the overall structure by integrating the contact function within the existing pixel area rather than adding peripheral elements.
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 enables efficient electrical connection of the cathode electrode to the contact electrode within the groove, reducing the display panel frame size and cost while maintaining the application of a predetermined potential, thereby addressing misalignment issues and enhancing manufacturing efficiency.
Implementation Method 1
an organic EL element employing a phenomenon in which electroluminescence of an organic material is used to obtain light emission when an electric field is applied to an organic thin film
Implementation Method 2
the cathode electrode is vacuum-deposited on the contact electrode provided on the outer periphery of the light-emitting pixel area
Data Source
AI summary
A display device of the present disclosure includes: an organic EL layer deposited on a circuit unit formed on a substrate via an insulating film; a cathode electrode deposited on the organic EL layer; a groove formed along a direction of arrangement of pixels between the pixels in the insulating film; and a contact electrode that is provided at a bottom of the groove and receives a predetermined potential. Moreover, the cathode electrode is electrically connected to the contact electrode in the groove.