Display Backlight Control for High External Illuminance Visibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display apparatuses face reduced visibility due to high external light illuminance, especially in environments like direct sunlight, where increasing backlight intensity is limited by performance constraints.
Innovation Solution
A display control apparatus that acquires external light illuminance, generates a correction image by compressing the dynamic range of the original image, and controls the backlight emission using a periodic control signal, either adjusting the duty cycle or switching to pulsed light emission based on illuminance levels, to enhance user-perceived brightness and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the backlight light amount is increased to improve visibility under high external light, then the visibility is improved, but the backlight performance limitations prevent further increase
Solution Approach 1:
The patent applies periodic action by controlling the backlight to emit light in pulses rather than continuously. The backlight controller generates a periodic control signal that turns the backlight on and off at specific intervals, creating pulsed light emission. This allows the backlight to achieve higher peak brightness during the on-period while maintaining acceptable average power consumption and heat generation, effectively overcoming the performance limitations of conventional continuous backlight operation.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the duty cycle of the backlight control signal based on external light conditions. When external illuminance exceeds a threshold, the system changes the duty cycle parameter to a specific range (10%-90%) to optimize the balance between peak brightness and average power consumption. This parameter adjustment enables the backlight to operate effectively within its performance constraints while maintaining visibility under high external light conditions.
2Illumination intensity
If image correction is applied to increase average brightness, then visibility is improved, but the dynamic range compression may reduce image quality
Solution Approach 1:
The patent applies partial action by selectively correcting only the luminance component of the image rather than processing the entire image data. The luminance corrector generates a corrected luminance signal that is then combined with the original chrominance signal. This partial correction approach increases the average brightness of the displayed image to counteract high external light conditions while minimizing the impact on overall image quality by preserving the original chrominance information and only adjusting the luminance portion.
3Illumination intensity
If the backlight is controlled with periodic signals to increase perceived brightness, then user-perceived brightness is improved, but the control complexity increases
Solution Approach 1:
The patent introduces an intermediary component, the backlight controller, that sits between the main control apparatus and the backlight unit. This intermediary device simplifies the overall system architecture by consolidating the periodic control signal generation and duty cycle adjustment functions within a dedicated controller module. The backlight controller receives control parameters from the main control apparatus and autonomously generates the appropriate periodic control signals, thereby reducing the control complexity of the overall system while achieving improved user-perceived brightness through pulsed backlight operation.
Data Source
AI summary
When illuminance E by external light is lower than a high threshold Th, a backlight controller performs a duty cycle control that adjusts an amount of light of the backlight by changing a duty cycle of the control signal in accordance with the illuminance amount by the external light while maintaining the control signal at a constant level. When the illuminance E by the external light is higher than the high threshold Th, the backlight controller performs a pulse control that causes the backlight to periodically emit a pulsed light by making the level of the control signal higher than the level of the control signal in the duty cycle control while fixing the duty cycle of the control signal at a predetermined value or lower.