OLED Pixel Circuit Initialization for Skip-Frame Luminance Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electroluminescent display apparatuses experience luminance deviations between refresh and skip frames due to insufficient initialization of light emitting diodes in skip frames, particularly in low-speed driving, leading to flicker issues.
Innovation Solution
An electroluminescent display apparatus with a pixel circuit that includes a driving transistor, a capacitor, and an initialization switch, which initializes nodes with specific voltages in both refresh and skip frames to maintain consistent luminance by equalizing programming voltages across frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the data refresh cycle is increased to reduce power consumption, then power consumption decreases, but luminance deviation between refresh frame and skip frame increases
Solution Approach 1:
The patent applies preliminary action by performing initialization operations on the light emitting device and related nodes before the emission period in both refresh frames and skip frames. This ensures that the light emitting device is properly prepared and initialized before emitting light, preventing luminance deviation even when the refresh cycle is extended. The initialization switch and capacitor are activated in advance to set correct voltage levels, maintaining consistent luminance across different frame types.
2Use of energy by moving object
If the number of skip frames is increased to extend data refresh cycle, then power consumption decreases, but luminance deviation between adjacent frames increases
Solution Approach 1:
The patent applies local quality by providing different initialization operations for refresh frames and skip frames based on their specific requirements. In refresh frames, both the first node (data voltage) and third node (light emitting device anode) are initialized, while in skip frames, only the third node is initialized since the first node retains its value from the previous refresh frame. This differentiated approach maintains luminance stability without requiring full re-initialization in every frame, enabling extended refresh cycles with consistent display quality.
3Device complexity
If initialization operation is omitted in skip frame to reduce complexity, then device complexity decreases, but luminance deviation occurs
Solution Approach 1:
The patent applies the taking out principle by extracting and separating the initialization operation for the third node (light emitting device anode) from the complete initialization sequence. Instead of initializing all nodes in every frame, the patent identifies that only the third node requires initialization in skip frames, while the first node (data voltage) is retained from the refresh frame. This selective initialization reduces operational complexity while maintaining luminance uniformity.
4Manufacturing precision
If full initialization operation is performed in every frame, then luminance uniformity is maintained, but power consumption increases
Solution Approach 1:
The patent applies periodic action by implementing initialization operations at appropriate intervals rather than continuously. The first node is initialized periodically in refresh frames, while the third node is initialized in both refresh frames and skip frames. This periodic approach ensures luminance uniformity is maintained through regular initialization while avoiding unnecessary continuous initialization operations that would waste power. The initialization switch and capacitor work together to provide timing-appropriate initialization.
Data Source
AI summary
An electroluminescent display apparatus includes a display panel including a plurality of pixels and a driving circuit configured to drive the display panel. Each of the plurality of pixels includes a light emitting device; a driving transistor configured to generate a driving current to be supplied to the light emitting device; a driving transistor controller including a capacitor, including one electrode connected to a first node charged with a data voltage and the other electrode connected to a second node connected to a gate electrode of the driving transistor, and a plurality of transistors configured to control a current flowing in the driving transistor; and an initialization switch configured to initialize a third node connected to an anode electrode of the light emitting device in response to a second gate control signal differing from the first gate control signal, in a skip frame period after the refresh frame period.