Display Device Initialization Voltage Adjustment for Low Refresh Rate Quality
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Solution Overview
Problem
Display devices face challenges in maintaining image display quality, particularly at low refresh rates in variable refresh rate modes, where black imperfections and flicker phenomena occur, affecting the visibility of low grayscale images.
Innovation Solution
A display device with sub-pixels that include a light emitting device and a driving transistor, where a reference voltage line applies an initialization voltage adjusted based on the length of the blank period, ensuring improved image display quality by compensating for characteristic value changes and reducing black imperfection phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the refresh rate is reduced to save power and increase frame holding time, then energy efficiency is improved, but black imperfections and flicker phenomena occur in low grayscale images
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the initialization voltage level based on the blank period length. When the refresh rate is reduced and blank period increases, the initialization voltage is increased to compensate for the longer charge leakage time, thereby preventing black imperfections while maintaining low power consumption operation.
Solution Approach 2:
The patent implements dynamics by making the initialization voltage adaptive rather than fixed. The voltage level changes dynamically according to the actual blank period length, allowing the display device to optimize between power savings at low refresh rates and image quality maintenance through increased initialization voltage when needed.
2Adaptability or versatility
If the blank period is extended to allow longer frame holding time, then refresh rate flexibility is improved, but voltage leakage increases causing black imperfections
Solution Approach 1:
The patent uses parameter changes by adjusting the initialization voltage level in response to varying blank period lengths. When blank period is extended for lower refresh rates, the initialization voltage is increased to compensate for the extended charge leakage time, thereby maintaining voltage stability and preventing black imperfections while preserving refresh rate flexibility.
3Device complexity
If a fixed initialization voltage is used to simplify circuit design, then device complexity is reduced, but image quality deteriorates at variable refresh rates
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed initialization voltage to a dynamic voltage that adapts to the blank period length. This allows the circuit to maintain simple structure while achieving variable refresh rate compatibility and consistent image quality across different refresh rates through automated voltage adjustment based on timing conditions.
Data Source
AI summary
A display device includes a sub-pixel comprising a light emitting device and a driving transistor DRT electrically connected to a first electrode of the light emitting device and configured to drive the light emitting device, and a reference voltage line electrically connected to the sub-pixel SP and applying an initialization voltage to the first electrode of the light emitting device, wherein a voltage level of the initialization voltage is changed according to a length of a blank period, thereby improving display quality of the image at a low refresh rate in a variable refresh rate mode.