Liquid Crystal Panel Backlight Timing Synchronization
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Solution Overview
Problem
Conventional display devices experience visual discomfort due to the asynchronous change in transmittance of the liquid crystal panel and backlight brightness, particularly during partial drive operations, where the backlight is lit before the liquid crystal panel's transmittance is sufficiently lowered, causing the panel to flash momentarily.
Innovation Solution
A display device with a first change unit for synchronizing transmittance changes in the liquid crystal panel and a second change unit for synchronizing backlight brightness changes, along with a calculation unit to determine a delay time for adjusting the backlight timing relative to the liquid crystal panel timing, ensuring synchronized changes to prevent visual discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the backlight is lighted at the dark part of the image during partial drive, then the contrast of the image is improved, but the liquid crystal panel flashes momentarily causing visual discomfort
Solution Approach 1:
The patent applies preliminary action by ensuring the liquid crystal panel's transmittance is sufficiently lowered before the backlight is lighted at the dark part of the image. The control unit monitors the transmittance change and only activates the backlight in the dark part after confirming the liquid crystal panel has reached the required low transmittance state, thereby preventing the flashing effect that causes visual discomfort while maintaining the contrast improvement benefit
2Illumination intensity
If the transmittance of the liquid crystal panel is changed by a large amount, then the brightness of the image can be adjusted significantly, but the transmittance cannot be changed promptly due to slow response speed
Solution Approach 1:
The patent implements feedback control by having the control unit continuously monitor the transmittance change of the liquid crystal panel and use this information to determine the appropriate timing for lighting the backlight. The control unit adjusts the backlight activation based on the actual transmittance state, ensuring synchronization even when the response speed is slow, thereby maintaining image quality without requiring rapid transmittance changes
3Device complexity
If the transmittance of the liquid crystal panel and brightness of the backlight are changed at the same timing, then the control is simplified, but visual discomfort occurs when response speed is slow
Solution Approach 1:
The patent uses preliminary action by requiring the liquid crystal panel to reach a sufficient transmittance change state before the backlight is activated. The control unit determines the backlight timing based on the actual transmittance state rather than using a fixed simultaneous timing, which prevents visual discomfort while adding minimal control complexity through conditional timing adjustment
Data Source
AI summary
Provided is a display device including a first change unit configured to change a transmittance of a liquid crystal panel in synchronization with a first timing, a second change unit configured to change brightness of a backlight of the liquid crystal panel in synchronization with a second timing, a calculation unit configured to calculate delay time for delaying the second timing relative to the first timing, and a delay control unit configured to make the first change unit change the transmittance of the liquid crystal panel in synchronization with the first timing, and make the second change unit change the brightness of the backlight in synchronization with the second timing delayed from the first timing by the delay time.