Display Device Backlight Timing Control for Black Stripe Elimination
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Solution Overview
Problem
Modern display devices face challenges in achieving satisfactory display quality due to differences in charging voltages between pixels in dimming regions, leading to unwanted black stripes caused by overlapping turn-on and turn-off periods of light source blocks and scan periods of dimming regions.
Innovation Solution
A display device design that includes a backlight unit with light source blocks and dimming regions, where the turn-on and turn-off periods of light source blocks are controlled to not overlap with the scan periods of dimming regions, using a backlight driver to manage light source driving signals and a panel driver to set optimized scan start times based on duty ratios, ensuring all pixels are scanned in either the turn-off or turn-on periods of corresponding light source blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the turn-on and turn-off periods of light source blocks are controlled to not overlap with the scan periods of dimming regions, then display quality is improved and black stripes are eliminated, but the control complexity increases
Solution Approach 1:
The backlight driver pre-calculates and sets the turn-on and turn-off periods of light source blocks based on the scan periods of dimming regions. By establishing these time intervals in advance, the system prevents overlapping between light source block operation and pixel scanning, thereby eliminating black stripes while managing control complexity through systematic timing planning.
Solution Approach 2:
The system dynamically adjusts the turn-on and turn-off periods of light source blocks according to the specific scan periods of different dimming regions. This dynamic timing control allows the backlight driver to adapt the illumination schedule to match the scanning sequence, ensuring that pixels are scanned during appropriate intervals and preventing display defects.
2Reliability
If all pixels are scanned in controlled light source block periods, then charging voltage differences are prevented, but the timing coordination between backlight driver and panel driver becomes more complex
Solution Approach 1:
The backlight driver receives timing information from the panel driver about the scan periods of dimming regions and uses this feedback to adjust the turn-on and turn-off periods of light source blocks. This feedback mechanism ensures that pixels are scanned during intervals when the corresponding light source blocks are in appropriate states, maintaining charging voltage uniformity while coordinating timing through systematic information exchange.
3Reliability
If the scan period of dimming regions is optimized based on duty ratios, then black stripes are eliminated, but the control precision requirements increase
Solution Approach 1:
The system uses duty ratios as a key parameter to determine and optimize the scan start times of dimming regions. By adjusting the timing parameters based on the duty cycle characteristics of light source blocks, the system achieves precise control over when pixels are scanned relative to light source illumination, thereby eliminating black stripes through parameter-based timing optimization.
Data Source
AI summary
A display device may include a backlight unit, a display panel, and a backlight driver, and a panel driver. The backlight unit may include light source blocks including a first light source block. The display panel may include dimming regions including a first dimming region and respectively overlapping the light source blocks. The first dimming region may overlap the first light source block. The backlight driver may control a turn-on period and a turn-off period of each of the light source blocks. The panel driver may sequentially provide scan signals to the dimming regions for controlling light transmission of the dimming regions. A turn-off period of the first light source block may start before a scan period of the first dimming region and may end after the scan period of the first dimming region. The first dimming region may receive corresponding scan signals in the scan period.