Local Dimming Backlight Control for Low-Brightness Uniformity
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Solution Overview
Problem
Conventional display devices experience compromised brightness uniformity at low gray-levels and low brightness due to the influence of threshold voltage and parasitic capacitance of thin film transistors, leading to poor frame quality.
Innovation Solution
The implementation of a local dimming function in the backlight source that adjusts brightness levels based on ambient light conditions and frame gray-level values, using different modes to control light-emitting units to maintain uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional display devices operate at low brightness or low gray-level, then energy consumption is reduced, but brightness uniformity is compromised due to threshold voltage and parasitic capacitance effects
Solution Approach 1:
The backlight source is divided into multiple independent light-emitting units that can be controlled separately. The controller selectively activates different light-emitting units based on the gray-level value being displayed, allowing low brightness operation with maintained uniformity by activating only the necessary portion of the backlight array.
Solution Approach 2:
Different regions of the backlight source are treated differently based on local requirements. The controller adjusts the brightness of specific light-emitting units corresponding to different gray-level regions, applying local dimming or boosting to compensate for threshold voltage and parasitic capacitance effects in specific areas of the display panel.
2Illumination intensity
If local dimming function uses first mode for low gray-level areas, then brightness uniformity is improved, but device complexity increases due to multiple control modes
Solution Approach 1:
The system dynamically switches between different control modes (first mode for low gray-level, second mode for high gray-level) based on real-time detection of the displayed image characteristics. This dynamic adaptation allows the system to optimize brightness uniformity for each scenario without requiring all control mechanisms to be active simultaneously, managing complexity through conditional activation.
Solution Approach 2:
The controller detects the gray-level value of the displayed frame and uses this feedback information to determine which control mode to apply. This feedback mechanism simplifies the control logic by using the detected gray-level information as the decision criterion for mode selection, rather than requiring complex predictive algorithms.
Data Source
AI summary
An electronic device includes a display panel and a backlight source. The backlight source is disposed below the display panel and includes light-emitting units. When the electronic device is in a low-brightness mode, the brightness of a white frame of the display panel is greater than 0 nit and less than or equal to 50 nits, and in a general mode, the brightness of the white frame of the display panel is greater than 50 nits. The backlight source includes a local dimming function. When in the low-brightness mode, the local dimming function is in a first mode. When in the general mode, the local dimming function is in a second mode.