Liquid Crystal Display Refresh Control for Pause Drive Brightness Mismatch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional liquid crystal display devices using pause drive with the CABC function experience reduced display quality due to abrupt changes in backlight intensity when transitioning from bright to dark images, as the screen is not refreshed every frame, leading to omitted images and mismatched brightness levels.
Innovation Solution
Implementing a transition period where the screen is refreshed in each phase of intensity change by adjusting the duration of the vertical display period to be less than or equal to the sub-transition period, ensuring the image displayed corresponds to the intended backlight intensity, and using a refresh rate control to maintain screen refresh during intensity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pause drive is performed to reduce power consumption, then power consumption is reduced, but display quality deteriorates due to omitted images and mismatched brightness levels
Solution Approach 1:
The patent segments the pause drive operation into distinct phases: a refresh period for screen updating and a no-refresh period for power saving. During the transition between bright and dark images, the system selectively performs refreshes only during necessary phases while pausing during others, thereby maintaining display quality during critical transitions while achieving power consumption reduction during stable display periods.
Solution Approach 2:
The patent implements periodic screen refreshes during pause drive by synchronizing the refresh period with the transition period of image brightness changes. The display control circuit performs refreshes at specific intervals (during the transition period) rather than continuously, creating a periodic action pattern that maintains image-backlight correspondence while reducing overall power consumption compared to continuous refresh.
2Reliability
If the backlight intensity is changed gradually during transition period, then display quality is improved, but the complexity of control increases
Solution Approach 1:
The patent employs feedback mechanisms where the display control circuit monitors the current display state and backlight intensity, then adjusts the refresh timing and pulse-width modulation duty cycle accordingly. The system detects when transitions between bright and dark images occur and dynamically adjusts the refresh period and backlight intensity in response, creating a closed-loop control system that manages complexity through intelligent responsiveness rather than rigid predetermined sequences.
3Reliability
If the refresh rate is maintained during transition period, then display quality is maintained, but power consumption increases
Solution Approach 1:
The patent dynamically adjusts the refresh rate based on the display content and transition state. During the transition period when image brightness changes occur, the system maintains higher refresh rates to ensure display quality. During stable display periods outside the transition period, the system reduces the refresh rate or enters pause drive mode with extended no-refresh periods, thereby creating a dynamic refresh strategy that adapts to operational conditions and optimizes the balance between display quality and power consumption.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided is a display device capable of suppressing reduction in display quality even when pause drive is performed, while allowing the intensity of a light source to be changed in accordance with images to be displayed. In a liquid crystal display device with the CABC function, 7. 5-Hz pause drive is performed. A transition period is provided in which images to be displayed are changed gradually from bright image X to dark image Y. In the transition period, the duration of a sub-transition period is five frames. Once the transition period starts, the duration of a vertical display period changes from eight frames to one frame. That is, 7.5-Hz pause drive switches to 60-Hz normal drive. In this manner, the duration of the vertical display period is set to be less than or equal to the duration of the sub-transition period, so that screen refresh is always performed in each sub-transition period of the transition period.