Backlight Current Compensation for Local Dimming Brightness Control
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Solution Overview
Problem
Conventional backlight modules continue to consume excessive power due to light-emitting areas emitting light even when displaying mostly black images, and deviations in brightness occur due to current signal loss and manufacturing errors, leading to inconsistent display quality.
Innovation Solution
A driving method for a backlight module with independent light-emitting areas, utilizing a driver chip to output initial, second, and third currents to compensate for current and brightness deviations through current sampling and brightness detection, ensuring actual brightness matches target brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light-emitting devices are controlled to emit light with predetermined brightness, then energy consumption is reduced, but brightness deviation occurs due to current signal loss and manufacturing errors
Solution Approach 1:
The patent implements a feedback mechanism where the actual brightness of each light-emitting area is detected and compared with the target brightness. Based on this comparison, a compensation current is generated and fed back to adjust the driving current of the light-emitting devices. This closed-loop feedback system ensures that brightness deviations caused by manufacturing errors or current signal loss are continuously corrected, maintaining consistent display quality while allowing energy-saving dimming operations.
2Loss of energy
If partition function is implemented with independent light-emitting areas, then power consumption is reduced, but brightness uniformity deteriorates due to current transmission losses
Solution Approach 1:
The patent applies local quality by implementing independent brightness detection and compensation for each light-emitting area. Each area has its own brightness sensor that detects local brightness characteristics, and the compensation current is calculated and applied specifically to that area. This localized approach allows each partitioned light-emitting area to maintain its own brightness uniformity despite current transmission losses, while the overall system benefits from reduced power consumption through selective dimming of dark areas.
3Measurement precision
If compensation currents are generated and output in multiple periods, then brightness accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements preliminary action by generating and applying compensation currents in multiple sequential periods within each frame display cycle. First, an initial compensation current is generated based on detected brightness deviation. Then, in a subsequent period, the actual brightness is re-detected and a second compensation current is generated to further refine the brightness accuracy. This multi-period preliminary compensation approach progressively eliminates brightness errors without requiring complete system redesign, managing complexity through time-sequenced operations.
Data Source
AI summary
Disclosed are a backlight module, a driving method thereof, and a display device. The method includes: in a first period t1, outputting an initial current by a driver chip to a light-emitting unit in a light-emitting area; obtaining a difference between the initial current and an actual current; generating a second current according to the difference between the initial current and the actual current; in a second period t2, outputting a second current by the driver chip to the light-emitting unit in the light-emitting area; and detecting the actual brightness of the light-emitting area, and determining a difference between the actual brightness and target brightness of the light-emitting area; generating a third current according to the difference between the actual brightness and the target brightness; and in a third period t3, outputting the third current by the driver chip to the light-emitting unit in the light-emitting area.