OLED Pixel Drive Circuit for Low-Luminance Flicker Control
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Solution Overview
Problem
Display devices using organic electro-luminescence (OLED) experience gradation loss and flicker at low luminance due to the inability to control display luminance by reducing backlight, leading to visible degradation in display quality.
Innovation Solution
A display device with a control circuit that adjusts the initialization potential and non-emission period based on luminance set values, using transistors and capacitors to manage light-emitting elements, reducing gradation loss and flicker by controlling the potential difference between the source and gate of the drive transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If black insertion is used to maintain low luminance in OLED displays, then luminance control is achieved, but flicker occurs and display quality deteriorates
Solution Approach 1:
The patent applies preliminary action by setting the initialization potential before the emission period begins. The control circuit sets the initialization potential to a higher value when low luminance is detected, which prepares the drive transistor gate to maintain stable operation throughout the subsequent emission period, preventing flicker and gradation loss before they occur.
Solution Approach 2:
The patent changes the electrical parameter (initialization potential) of the drive transistor gate based on the detected luminance level. When low luminance is detected, the initialization potential is increased, which alters the gate-source voltage characteristics to maintain stable current flow through the light-emitting element, thereby eliminating flicker and improving display quality at low luminance settings.
2Illumination intensity
If the number of gradations is reduced at low luminance, then luminance control is achieved, but gradation loss occurs
Solution Approach 1:
The patent changes the initialization potential parameter based on luminance level to maintain adequate voltage headroom for gradation representation. By setting a higher initialization potential at low luminance, the gate-source voltage can still accommodate sufficient voltage steps for gradation, preventing gradation loss while maintaining the desired low luminance output.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses display quality degradation at low luminance by minimizing gradation loss and flicker, ensuring consistent image quality across varying luminance settings.
Implementation Method 1
a light-emitting element configured to emit light by a current flowing therethrough
Data Source
AI summary
A display device includes a display area including a plurality of pixels arrayed next to one another in a first direction and in a second direction that is different from the first direction, and a control circuit, wherein each of the pixels includes a light-emitting element configured to emit light by a current flowing therethrough, a drive transistor, a shut-off transistor, and a holding capacitance.