Organic Light Emitting Display Test Circuit for Transistor Defect Detection
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Solution Overview
Problem
Organic light emitting display devices face defects in switching transistors that can lead to pixel malfunction, which are difficult to detect during manufacturing, affecting the device's performance and reliability.
Innovation Solution
An organic light emitting display device with a test circuit that applies specific signals to determine the normal operation of transistors by analyzing voltage levels, allowing for the detection of defects during the manufacturing process, including a configuration of transistors and capacitors within each pixel to assess the functionality of the organic light emitting diode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a test circuit is added to detect transistor defects, then manufacturing reliability is improved, but device complexity increases
Solution Approach 1:
The pixel circuit is divided into functional modules (switching transistor, light emitting diode, capacitor) with dedicated test signal paths. The test circuit segments the detection function by applying specific test signals to different transistor gates independently, allowing defect identification without testing the entire display device.
Solution Approach 2:
A test signal is introduced as an intermediary to mediate between the test circuit and the transistor being tested. This test signal acts as a mediator that activates specific transistors in a controlled manner, enabling indirect observation of transistor functionality through voltage level measurements without requiring direct physical access to the transistor.
2Manufacturing precision
If comprehensive testing is performed on all pixels, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The test circuit performs preliminary defect detection during the manufacturing process before the display device is finalized. By conducting tests at this early stage using simplified test signals and voltage level measurements, defects are identified and flagged before integration, avoiding the need for complex post-manufacturing testing and rework.
Solution Approach 2:
The testing method changes operational parameters by applying specific voltage levels (first level, second level, third level) to test signals at different time points. This parameter variation allows the test circuit to differentiate between normal and defective transistors based on their voltage responses, achieving comprehensive testing through controlled parameter manipulation rather than physical inspection.
3Measurement precision
If multiple test signals are applied to each pixel, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The test circuit employs periodic action by applying test signals at specific time points (first time point, second time point, third time point) rather than continuously. Each time point corresponds to a specific voltage level application, allowing the system to capture transient states of transistors periodically. This periodic measurement approach achieves comprehensive transistor state determination while minimizing total testing time compared to continuous monitoring.
Data Source
AI summary
Provided is an organic light emitting display device including: a display unit including a plurality of pixels, each pixel of the pixels including an organic light emitting diode; and a test circuit configured to apply a first signal and a second signal to the display unit and to receive a third signal from the display unit. The test circuit is configured to determine whether or not the display unit is in a normal state based on a voltage level of the third signal when the first and second signals have a first level.