Pixel including first through fourth transistors and display device including the same
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Solution Overview
Problem
Existing pixels in display devices face challenges in applying to high-resolution displays due to the inclusion of a large number of transistors and capacitors, which complicates the design and functionality.
Innovation Solution
A pixel design incorporating four transistors and one capacitor, specifically configured to compensate for the threshold voltage of a driving transistor, allowing for stable operation in high-resolution displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of transistors and capacitors are included in the pixel to compensate for threshold voltage, then the threshold voltage compensation is improved, but the device complexity increases making it difficult to apply to high-resolution displays
Solution Approach 1:
The patent merges the threshold voltage compensation function and the data writing function into a single operational phase. The second transistor remains continuously turned on during both the compensation period (when the third transistor is on) and the data writing period, eliminating the need for separate transistor switching sequences and reducing the number of required transistors and capacitors while maintaining effective threshold voltage compensation.
2Productivity
If the second transistor is turned on before the fourth transistor to write data early, then the productivity is improved, but the luminance uniformity deteriorates due to insufficient compensation
Solution Approach 1:
The patent implements preliminary threshold voltage compensation by keeping the second transistor continuously turned on before data writing. The compensation is performed in advance during the period when the third transistor is turned on, ensuring that the driving transistor's threshold voltage is fully compensated before the data signal is written, thereby maintaining luminance uniformity while enabling timely data writing.
3Reliability
If the second transistor is turned off after the fourth transistor to extend compensation period, then the threshold voltage compensation is improved, but the productivity decreases due to delayed data writing
Solution Approach 1:
The patent maintains continuous useful action by keeping the second transistor turned on throughout both the compensation period and the data writing period without interruption. This continuous operation ensures that threshold voltage compensation is effectively performed while simultaneously allowing data writing to proceed without delay, as the second transistor's continuous conduction enables both functions to occur in sequence within the same operational window.
Data Source
AI summary
A pixel includes a light emitting element, a first transistor having a first electrode connected to a first power line via a first node, a second electrode connected to a second power line via a second node and the light emitting element, and a gate electrode connected to a third node, a second transistor connected between a data line and the third node, and having a gate electrode connected to a first scan line, a third transistor connected between the first power line and the first node, and having a gate electrode connected to an emission control line, and a fourth transistor connected between the second node and a third power line. The second transistor is turned on after the fourth transistor is turned on and maintains a turn-on state during a predetermined period, and is turned off before the fourth transistor is turned off.