OLED Pixel Drive Circuit Initialization for Luminance Uniformity
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Solution Overview
Problem
Display devices using OLEDs suffer from luminance non-uniformity due to changes in the power supply potential, leading to moving image blurring and degraded display quality, particularly when displaying moving pictures.
Innovation Solution
A display device with a control circuit that initializes and sets specific potentials for each pixel, using a holding capacitance and drive transistor to regulate the voltage across the light-emitting element, ensuring uniform luminance by generating initialization voltage signals that correct for variations in threshold voltage and power supply potential drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a black screen is inserted before writing display data to reset the potential in conventional OLED display devices, then moving image blurring is reduced, but luminance non-uniformity occurs when power supply potential changes
Solution Approach 1:
The patent applies preliminary action by writing initialization potentials to the gates of drive transistors before writing video data. This pre-initialization step sets a known reference state for all pixels, ensuring that subsequent video writing operates from a consistent baseline. The initialization potential writing occurs in a preliminary phase before the main video data writing, preventing luminance non-uniformity that would otherwise occur due to residual potentials from previous frames or power supply variations.
2Ease of operation
If power supply potential changes occur in OLED display devices, then device operation is maintained, but luminance non-uniformity occurs across the display screen
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the initialization potential values based on detected power supply potential variations. When power supply potential changes are detected, the system modifies the initialization potential parameters written to pixel gates to compensate for the change. This parameter adjustment ensures that the voltage across each light-emitting element remains consistent, maintaining uniform luminance across the display screen even when power supply conditions vary.
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 prevents luminance non-uniformity across the display screen, enhancing the display quality of moving images by maintaining consistent pixel illumination levels.
Implementation Method 1
a light-emitting element configured to emit light by a current flowing therethrough
Implementation Method 2
a holding capacitance coupled between the source and a gate of the drive transistor
Data Source
AI summary
A display device is provided and includes display area including pixels arrayed next to one another in first direction and in second direction that is different from first direction, wherein pixels include light-emitting element configured to emit light by current flowing therethrough, drive transistor, and holding capacitance, while one terminal of light-emitting element is coupled to one of source and drain of drive transistor, first potential is supplied to other terminal of light-emitting element, second potential that is higher than first potential is supplied to other one of source and drain of drive transistor, holding capacitance is coupled between source and gate of drive transistor, and display device being configured to write initialization potentials into gates of respective drive transistors in accordance with voltage across drain and source of drive transistor, then write video writing potentials into the gates of the respective drive transistors.