PM-LED Display Scan Pre-Charge Circuit for Image Sticking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional passive matrix light-emitting diode (PM-LED) display panels face issues with image sticking and long-term or excessive reverse bias of LEDs due to parasitic capacitors, leading to reduced lifespan and incorrect lighting of unlit LEDs.
Innovation Solution
A novel driving method and control circuit that includes a scan pre-charge circuit to discharge non-active scan lines during non-display periods, preventing upward image sticking, and a data pre-discharge circuit to manage parasitic capacitors on data lines, ensuring LEDs are not wrongly lit and reducing reverse bias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-charge circuit is coupled to scan lines and pre-discharge circuit is coupled to data lines, then image sticking is prevented, but LEDs are subjected to long-term reverse bias and excessive reverse voltage
Solution Approach 1:
The patent applies preliminary action by pre-charging scan lines and pre-discharging data lines before the actual display operation. This prepares the electrical state of the lines in advance to prevent image sticking, while the control method carefully manages the timing and voltage levels to avoid subjecting LEDs to excessive reverse bias that would damage them.
Solution Approach 2:
The patent changes voltage parameters dynamically during different operation phases. During non-display periods, scan lines are pre-charged to specific voltage levels and data lines are pre-discharged to appropriate levels, ensuring that when display operation begins, LEDs are in the correct bias state without experiencing damaging reverse voltage conditions.
2Productivity
If display time is divided into several equal parts for time division multiplexing, then refresh rate is improved, but switching operations cause image sticking
Solution Approach 1:
The patent implements periodic action by dividing the display time into multiple subframe periods with regular time division multiplexing. Each subframe period systematically activates specific scan lines and data lines in sequence, enabling high refresh rates while the periodic pre-charge and pre-discharge operations prevent image sticking at each switching transition.
Solution Approach 2:
Before each switching operation in the time division multiplexing sequence, the patent performs preliminary pre-charging of scan lines and pre-discharging of data lines. This preparatory action ensures clean transitions between subframe periods, maintaining high refresh rates without image sticking artifacts.
3Area of stationary object
If multiple scan lines are scanned sequentially during subframe periods, then display coverage is improved, but unlit LEDs remain in reverse bias state for long periods
Solution Approach 1:
The patent segments the display operation into multiple subframe periods, where each subframe period is dedicated to scanning specific scan lines. This segmentation allows systematic control of which LEDs are active and which are inactive, enabling the pre-discharge circuit to manage reverse bias conditions for unlit LEDs in each segment separately, preventing prolonged reverse bias exposure.
Data Source
AI summary
The present invention provides a method of controlling a display panel. The display panel includes a plurality of subpixels and a plurality of scan lines coupled to the plurality of subpixels. The method includes steps of: scanning a first scan line among the plurality of scan lines to turn on at least one of the plurality of subpixels coupled to the first scan line during a subframe period among a display frame period; and discharging a second scan line among the plurality of scan lines during a non-display period following the subframe period. Wherein, the second scan line is different from the first scan line.