Pixel Circuit Ripple Blocking Switch for OLED Uniformity
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Solution Overview
Problem
The existing pixel circuits in organic light emitting display devices suffer from image quality deterioration due to ripples in the low-potential power supply voltage, leading to non-uniformity in the state of charge between pixel lines and differences in luminance between pixel lines.
Innovation Solution
The proposed pixel circuit includes a driving element, first and second switch elements, and a capacitor. The first switch element is turned on by a scan pulse to supply a data voltage, while the second switch element is turned off by a light emitting control pulse to block the electric current path between the driving element and the light emitting element, thereby alleviating the ripple defect in the low-potential power supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a low-potential power supply voltage is commonly applied to the pixels, then power supply efficiency is improved, but voltage ripples are generated causing image quality deterioration
Solution Approach 1:
A second switch element is introduced as an intermediary component between the light emitting element and the low-potential power supply voltage. This switch element blocks the current path during specific periods to prevent voltage ripples from affecting the light emitting element, thereby eliminating the harmful effect while maintaining the power supply efficiency benefit
2Object-affected harmful factors
If the second switch element blocks the current path during ripple periods, then image quality is improved, but additional circuit complexity is introduced
Solution Approach 1:
The second switch element is merged with the existing pixel circuit structure, sharing common nodes and integrating seamlessly with the driving element and light emitting element. This combination approach adds the necessary ripple-blocking function while minimizing the increase in circuit complexity
Data Source
AI summary
A pixel circuit and a display device including the same are disclosed. The pixel circuit of this disclosure includes a driving element including a first electrode connected to a first node to which a pixel driving voltage is applied, a gate electrode connected to a second node, and a second electrode connected to a third node, and configured to supply an electric current to a light emitting element; a first switch element configured to be turned on according to a gate-on voltage of a scan pulse to supply a data voltage to the second node; and a second switch element configured to be turned off according to a gate-off voltage of a light emitting control pulse generated in antiphase of the scan pulse.