Pixel Circuit Timing Control for OLED Color Shift Reduction
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Solution Overview
Problem
Existing display technologies suffer from a color shift phenomenon in light-emitting elements due to variations in current density, which affects the wavelength and distorts the displayed image.
Innovation Solution
A pixel structure is designed with specific transistor configurations and capacitors to control the turn-on time points and current supply to light-emitting elements, ensuring consistent current application regardless of data voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current density varies in light-emitting elements, then the wavelength changes and color shift occurs, but maintaining consistent current density requires complex transistor control circuits
Solution Approach 1:
The patent applies preliminary action by pre-setting the turn-on time points of transistors based on data voltage levels before current supply begins. The control circuit determines turn-on timing in advance using the relationship between data voltage and transistor threshold voltages, ensuring consistent current density without requiring complex real-time adjustment mechanisms during operation.
Solution Approach 2:
The patent utilizes parameter changes by varying the turn-on time points of transistors according to data voltage levels. By changing the timing parameter of transistor activation rather than adjusting current magnitude directly, the circuit achieves consistent current density while maintaining simpler circuit architecture compared to active current regulation methods.
2Reliability
If multiple transistors are used to control turn-on time points, then current consistency improves, but the pixel structure becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the current control function across multiple transistors (first transistor for initial current supply, second transistor for interrupting current). Each transistor is assigned a specific turn-on time point based on data voltage, and their coordinated operation ensures consistent current supply to the light-emitting element while distributing the control complexity across separate components.
Solution Approach 2:
The patent implements feedback by using the data voltage level itself to determine the turn-on time points of the transistors. The control circuit monitors the data voltage and automatically adjusts when each transistor should activate, creating a closed-loop system that ensures consistent current density without requiring external intervention or complex programming.
3Stability of the object's composition
If turn-on time points are determined by data voltage, then color shift is reduced, but the control mechanism becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-determining the turn-on time points of transistors based on data voltage levels before current supply begins. The control circuit calculates and sets the appropriate turn-on timing in advance using the known relationship between data voltage and transistor threshold voltages, ensuring consistent current density and stable color output without requiring complex real-time adjustment mechanisms during operation.
Data Source
AI summary
A pixel includes a second transistor having a control electrode connected to a first node, a first electrode for receiving a first power voltage, and a second electrode connected to a second node, a first transistor having a gate electrode connected to the second node, a first electrode for receiving the first power voltage, and a second electrode connected to a third node, and a light-emitting element configured to be supplied with a driving current from the first transistor, wherein a turn-on time point of the second transistor is determined by a data voltage, and wherein the driving current supplied to the light-emitting element is configured to be interrupted as the second transistor is turned on.