Display Panel Transistor Inspection via Control Voltage Sweep
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Solution Overview
Problem
Existing technologies face challenges in effectively inspecting the properties of driving transistors in display panels, which can lead to abnormal pixel operation if the transistors are not functioning correctly.
Innovation Solution
A method is provided for inspecting a display panel by applying voltages to a first transistor, varying the control voltage levels, and measuring the current flowing through the transistor to assess its on and off states, utilizing a series of scan and initialization signals to control transistor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inspection methods are used to measure driving transistor properties, then measurement capability is provided, but the measurement process is complex and difficult to implement
Solution Approach 1:
The patent extracts the driving transistor from the pixel circuit by applying specific voltages to turn off other transistors (ELVDD to first electrode, ELVSS to second electrode, and threshold voltage to control electrode). This isolation allows dedicated measurement of the driving transistor's on-current and off-current without interference from other circuit elements, resolving the complexity of conventional inspection methods.
Solution Approach 2:
The patent applies preliminary voltage configurations before measurement to prepare the transistor in specific states. By pre-applying ELVDD, ELVSS, and control voltages to turn other transistors off, the measurement process is simplified and can be systematically performed for all pixels in the display panel.
2Reliability
If driving transistor properties are not inspected, then device complexity is reduced, but pixel operation becomes abnormal and reliability decreases
Solution Approach 1:
The patent enables self-inspection of driving transistors using the pixel's own structure and available voltage lines. By utilizing existing transistors (ELVDD, ELVSS, control voltage lines) and applying specific voltage combinations, the inspection process becomes integrated into the manufacturing flow without requiring external specialized equipment, thus improving reliability while managing complexity.
3Measurement precision
If multiple voltage levels are applied to inspect transistor properties, then measurement accuracy is improved, but the inspection process becomes more time-consuming
Solution Approach 1:
The patent employs periodic voltage application sequences to measure different transistor properties. By systematically applying ELVDD/ELVSS voltages followed by control voltages in repeating cycles, the inspection process efficiently captures both on-current and off-current characteristics. This periodic approach allows parallel processing across multiple pixels, reducing total inspection time while maintaining measurement precision.
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 method allows for efficient and accurate measurement of transistor properties, ensuring normal pixel operation and improving the reliability of display panels by identifying and addressing any abnormalities in the driving transistors.
Implementation Method 1
measuring a current flowing through the first transistor via a data line connected to the first electrode of the first transistor
Data Source
AI summary
A method for inspecting a display panel includes in a pixel comprising a light emitting element and a first transistor connected to the light emitting element, applying a first voltage to a first electrode of the first transistor; applying a second voltage having a lower level than the first voltage to a second electrode of the first transistor; applying a control voltage to a control electrode of the first transistor; gradually varying a level of the control voltage such that the level of the control voltage is lowered; and measuring a current flowing through the first transistor via a data line connected to the first electrode of the first transistor, wherein an initial level of the control voltage is the same as the level of the first voltage.