Pixel Circuit Parallel Switches for Voltage Ripple Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display devices, particularly organic light emitting display devices, face significant issues with low-potential power supply voltage ripples due to rapid changes in voltage at the source node of driving elements, leading to in-plane charging unevenness and increased ripple effects across pixel lines.
Innovation Solution
The implementation of a pixel circuit design where two switch elements are connected in parallel to an initialization voltage line, allowing for shared initialization pulses across spaced-apart pixel lines, thereby reducing the voltage drop at the source node and minimizing low-potential power supply voltage ripples during charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar cathode electrode structure is applied to all pixels, then the manufacturing process is simplified, but the low-potential power supply voltage ripple increases due to rapid voltage changes at the source node
Solution Approach 1:
The pixel circuit is divided into multiple switching elements (first switching element, second switching element, third switching element) that operate at different times. The initialization is segmented into two stages: first initialization through the first switching element, then second initialization through the second switching element after the first is turned off. This temporal segmentation prevents simultaneous charging currents from multiple pixels, reducing power supply voltage ripple while maintaining the simple planar cathode electrode structure.
2Speed
If the voltage of the source node is rapidly changed during charging, then the charging speed is improved, but the low-potential power supply voltage ripple is generated
Solution Approach 1:
The first switching element is turned on to perform preliminary initialization of the source node before the second switching element is activated. This preliminary action prepares the circuit state, and the sequential operation ensures that when the second switching element charges the source node, the first switching element is already off, preventing conflicting charging currents that would cause ripple while still achieving rapid voltage changes.
3Productivity
If multiple pixel lines are charged simultaneously, then the productivity is improved, but the in-plane charging unevenness occurs due to mutual interference
Solution Approach 1:
The switching elements operate in periodic cycles with distinct timing phases. Each pixel line's initialization follows a periodic sequence: first switching element on, then off, followed by second switching element on. This periodic timing control ensures that adjacent pixel lines are charged in staggered phases rather than simultaneously, eliminating mutual interference and ensuring uniform charging across the display panel while maintaining high productivity through the systematic cycling.
Data Source
AI summary
A pixel circuit and a display device including the pixel circuit are disclosed. The pixel circuit according to embodiments includes a first pixel circuit connected in parallel to an initialization voltage line to which an initialization voltage is applied, and including a first-first switch element connected to a first-first gate line and a first-second switch element connected to a first-second gate line; and a second pixel circuit connected in parallel to the initialization voltage line, and including a second-first switch element connected to a second-first gate line and a second-second switch element connected to a second-second gate line, and the first-second gate line and the second-first gate line are electrically connected.