OLED Subpixel Test Circuit for AC Short Dark Spot Detection
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Solution Overview
Problem
It is difficult to confirm whether dark spots in light emitting display devices are caused by an AC short circuit between the anode and cathode electrodes, making it challenging to address this defect effectively.
Innovation Solution
Incorporating a test transistor between neighboring subpixels in a row line, allowing for a current path to be formed when the transistor is turned on, with the cathode electrode in a floating state during a test process, enabling detection of AC short circuits by comparing light emission patterns during normal and cathode floating driving modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test transistor is added to enable AC short circuit detection, then detection precision is improved, but device complexity increases
Solution Approach 1:
The display device is segmented into functional units (subpixels) with test transistors strategically placed in row lines. Each test transistor operates independently to detect AC short circuits in its corresponding subpixel, enabling localized detection without requiring system-wide complexity.
Solution Approach 2:
The test transistor acts as an intermediary component between the anode and cathode electrodes. By controlling the formation of current paths through the test transistor, the system can indirectly detect AC short circuits without directly measuring the problematic current path, simplifying the detection mechanism.
2Difficulty of detecting and measuring
If test transistors are integrated into row lines to form current paths, then detection capability is improved, but manufacturing complexity increases
Solution Approach 1:
The test transistor is merged with the existing row line structure of the display device. The test transistor shares the same fabrication process and structural framework as the display transistors, allowing the detection functionality to be integrated without adding separate manufacturing steps or processes.
Solution Approach 2:
The test transistor serves multiple functions: it acts as a switching element for forming current paths during detection, and its structure is compatible with the standard display device manufacturing process. This multi-functionality reduces the need for separate dedicated detection components.
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
Enhances the detection rate of dark spot defects caused by AC short circuits by accurately identifying affected subpixels through distinct light emission patterns, improving diagnostic accuracy.
Implementation Method 1
light emitting display devices equipped with light emitting elements such as light emitting diodes emit light when charges are injected into a light emitting layer formed between an anode electrode and a cathode electrode, and electrons and holes are paired and then extinguished
Data Source
AI summary
A light emitting display device includes a substrate having a display region in which subpixels are arranged along row lines and column lines, and a light emitting diode in the subpixel. The light emitting diode includes an anode electrode, a light emitting layer on the anode electrode, and a cathode electrode on the light emitting layer. The display device further includes a test transistor in the row line and including a source electrode connected to the anode electrode of one of neighboring subpixels in the row line and a drain electrode connected to the cathode electrode of the other of the neighboring subpixels in the row line, and a test gate line connected to a gate electrode of the test transistor. When the test transistor is turned on and a current path is formed in the row line, the cathode electrode is in an electrically floating state.