Display Panel Pixel Defect Detection via Shared Test Transistor
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Solution Overview
Problem
Existing display panels lack an effective method to test for defective pixels, which can lead to malfunction and reduced display quality.
Innovation Solution
A method and structure for testing display panels that includes applying specific power supply voltages and signals to transistors and light emitting elements, using a test transistor to measure sensing voltages and determine transistor defects, allowing for identification of defective pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a test method for display panels is implemented, then defective pixels can be detected, but device complexity increases due to additional test transistors and signaling requirements
Solution Approach 1:
The test transistor shares the same gate electrode structure with the switching transistor, allowing the same physical component to serve both switching functions during normal operation and testing functions during quality control. The gate electrode is reused to apply both scan signals during display operation and test voltages during defect detection, eliminating the need for completely separate test components.
Solution Approach 2:
The data line serves as an intermediary pathway that carries both data signals during normal operation and sensing voltages during testing. By utilizing the existing data line infrastructure, the patent avoids creating dedicated test signal pathways, thereby reducing overall system complexity while enabling defect detection functionality.
2Measurement precision
If multiple power supply voltages and test signals are applied to test transistors, then accurate defect detection is achieved, but energy consumption increases during testing
Solution Approach 1:
The testing process is implemented as a periodic operation that occurs at specific intervals (such as during manufacturing quality control or at scheduled maintenance periods) rather than continuously. During normal display operation, the test transistor remains inactive, consuming minimal energy. The full test sequence with multiple voltage levels is applied only when needed for defect detection.
Solution Approach 2:
The test method utilizes controlled changes in voltage parameters (applying different power supply voltages and test signals) to detect defects. By systematically varying voltage levels and measuring responses, the system achieves accurate defect detection. The parameters are changed only during the brief testing window, not during continuous operation.
Data Source
AI summary
A method of testing a display panel including a pixel coupled to first, second, and third power lines, a data line, scan lines, an emission control line, and a test line, the method includes: applying a first power supply voltage to the first power line; applying a test voltage having a turn-on voltage level to the second power line; applying a scan signal having a turn-on voltage level sequentially to the scan lines and an emission control signal having a turn-on voltage level to the emission control line; applying a gate signal to the test line to turn on a test transistor coupled between two electrode of a light emitting element included in the pixel; measuring a sensing voltage output through the data line; and determining whether the pixel is defective, based on a voltage level of the measured sensing voltage.