Display Device Non-Emission Period Control for Parasitic Coupling
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Solution Overview
Problem
Display devices face challenges in improving image quality due to parasitic capacitor coupling, which affects luminance and can cause distortion, especially at lower luminance levels.
Innovation Solution
A display device and method that control the off-duty of an emission control signal and the supply timing of a first scan signal based on a dimming signal, adjusting the width of non-emission periods and the timing of scan signals to minimize parasitic capacitor coupling and enhance luminance consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the emission control signal is continuously supplied to maintain high luminance, then the luminance output is improved, but parasitic capacitor coupling occurs causing luminance distortion
Solution Approach 1:
The emission control signal is supplied periodically with alternating on-duty and off-duty periods. During off-duty periods, the signal is interrupted to allow parasitic capacitor discharge, preventing coupling distortion. This periodic interruption resolves the contradiction by maintaining luminance through regular on-periods while eliminating parasitic effects through controlled off-periods.
Solution Approach 2:
Off-duty periods are strategically positioned before critical emission phases to preemptively discharge parasitic capacitors. By performing the discharge action in advance (during off-duty periods before data writing and emission), the system prevents parasitic capacitor coupling from occurring during critical luminance generation phases.
2Object-generated harmful factors
If off-duty periods are increased to reduce parasitic capacitor coupling, then luminance distortion is reduced, but the overall emission time is decreased
Solution Approach 1:
Off-duty periods are strategically positioned at specific locations within the frame period rather than uniformly distributed. The timing and duration of off-duty periods are locally optimized to occur when parasitic capacitor discharge is most beneficial, while minimizing impact on overall emission time. This localized approach resolves the contradiction by targeting parasitic discharge to critical moments without sacrificing total luminance output.
Data Source
AI summary
A display device includes a pixel having a first transistor connected between first and second nodes to generate a driving current; an emission driver that supplies an emission control signal including an off-duty corresponding to first and second gate-off periods to an emission control line during a frame period; a scan driver that supplies first to fourth scan signals to the first to fourth scan lines in a first non-emission period, respectively, and that supplies the first scan signal to the first scan line in a second non-emission period; a data driver that supplies a data signal to the data line; and a controller adjusting the off-duty of the emission control signal that is a width of each of the first and second non-emission periods in response to a dimming signal, and that controls a timing at which the first scan signal is supplied in the second non-emission period.