Pixel Circuit Defect Detection Using Sequential Transistor Activation
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Solution Overview
Problem
The existing methods for inspecting display panels fail to effectively detect defects in pixel circuits, particularly in thin film transistors, which can lead to improper driving current provision to light emitting elements, resulting in manufacturing inefficiencies and defects.
Innovation Solution
A method involving the application of specific test voltages to nodes connected to transistors and capacitors within the pixel circuit, utilizing a sequence of transistor activations to detect defects by measuring voltages and currents, thereby identifying and potentially repairing faulty components before subsequent manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing inspection methods are used for display panels, then the inspection process is simple, but defects in pixel circuits particularly in thin film transistors cannot be effectively detected
Solution Approach 1:
The inspection method applies preliminary actions by sequentially activating specific transistors (third transistor to apply first test voltage, fourth transistor to apply second test voltage, fifth transistor to apply third test voltage) before final defect detection. This staged approach allows systematic testing of pixel circuit components including thin film transistors and capacitors, enabling effective defect detection while managing complexity through structured test sequences
Solution Approach 2:
The method changes electrical parameters by applying multiple different test voltages (first test voltage, second test voltage, third test voltage) to different nodes of the pixel circuit. By varying voltage levels and applying them to specific transistors and capacitors in sequence, the inspection can detect defects that would not be apparent with a single test condition, thereby improving measurement precision without requiring overly complex equipment
2Productivity
If no inspection is performed on pixel circuits, then manufacturing time is reduced, but defects lead to improper driving current provision to light emitting elements causing manufacturing waste
Solution Approach 1:
The inspection is performed as a preliminary step before final assembly and packaging. By conducting the transistor activation sequence and voltage application tests at this early stage, defects are identified before they propagate to subsequent manufacturing steps, preventing waste of time and resources on defective components while maintaining overall manufacturing efficiency
Solution Approach 2:
The pixel circuit components themselves (transistors and capacitors) are used to perform the inspection function. By activating existing transistors in specific sequences and measuring their response to test voltages, the circuit under test serves its own inspection function, eliminating the need for separate complex testing equipment and maintaining productivity while ensuring reliability
Data Source
AI summary
A method of inspecting a display panel includes testing a pixel circuit including a plurality of transistors and a capacitor in the display panel. The testing of the pixel circuit includes: providing a first test voltage to a first node to which a first electrode of the capacitor is connected, providing a second test voltage different from the first test voltage to a second node to which a second electrode of the capacitor is connected, and detecting a defect in the pixel circuit through a test transistor connected to the first node among the plurality of transistors.