Hybrid Backlight Control for Local Dimming and Privacy Modes
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Solution Overview
Problem
Existing edge-lit type backlights in display devices face challenges in performing local dimming control, which affects the display quality of images, especially when trying to switch between privacy and public modes, as they struggle to balance light emission angles and maintain image clarity.
Innovation Solution
A display device with a combination of direct-lit and edge-lit backlights, where the control unit manages light sources and optical effects to selectively emit light in specific angles, allowing for improved local dimming control and adjustable display modes by switching between different light source configurations and emission periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If edge-lit type backlight is used, then device complexity is reduced, but local dimming control cannot be performed
Solution Approach 1:
The backlight unit is divided into multiple independent light sources (first and second light sources) that can be controlled separately. Each light source can be independently switched on and off, enabling local dimming control while maintaining the simpler edge-lit structure.
Solution Approach 2:
The patent implements dynamic switching between different display modes (first and second display modes) by controlling different light sources at different times. The control unit dynamically adjusts which light sources are active based on the current display mode, enabling flexible local dimming functionality.
2Ease of operation
If first directional backlight makes second directional backlight direct-lit type, then local dimming control is enabled, but display quality deteriorates
Solution Approach 1:
The patent uses time-division multiplexing where the first and second light sources are activated in alternating periods. During the first display mode, the first light source is active; during the second display mode, the second light source is active. This periodic switching enables local dimming control without requiring both light sources to be simultaneously optimized for direct-lit configuration.
Solution Approach 2:
The system dynamically switches between different light source configurations based on display mode. The control unit adjusts which light sources are active to maintain optimal display quality for the current mode while enabling local dimming functionality when needed.
3Object-affected harmful factors
If light emission angle is regulated, then privacy mode is achieved, but viewing angle is limited
Solution Approach 1:
The patent implements dynamic switching between privacy mode and public mode by controlling different light sources. In privacy mode, the first light source with regulated emission angle is active to prevent viewing from side angles. In public mode, the second light source is active to allow wider viewing angles. This dynamic adaptation resolves the contradiction between privacy protection and viewing flexibility.
Solution Approach 2:
The system changes the emission angle parameter by switching between different light sources with different optical characteristics. The first light source provides narrow emission angles for privacy, while the second light source provides wide emission angles for public viewing. This parameter switching enables the display to adapt to different viewing requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances display quality by allowing for precise light control, ensuring images are clear and visible from intended angles while maintaining privacy, without significant deterioration in display quality during mode changes.
Implementation Method 1
a first light control unit that imparts an optical effect to light emitted from the plurality of first light sources, does not regulate emission of light in a first angle range around a first direction having an angle with respect to the first main surface, and regulates emission of light in a second angle range around a second direction having an angle different from the angle in the first direction with respect to the first main surface
Implementation Method 2
a second light control unit that imparts an optical effect to light emitted from the second light source and causes the light to be emitted at least in the second angle range
Data Source
AI summary
A display device includes a display panel, an illumination device, and a control unit, in which, when performing display in a first display mode, the control unit corrects an image signal to generate a correction signal, writes a first image based on the correction signal in the display panel, leaves a second light source unlit, and selectively turns on a plurality of first light sources based on the correction signal, and when performing display in a second display mode, the control unit generates a correction signal, writes a first image in the display panel, leaves the second light source unlit, and selectively turns on the plurality of first light sources based on the correction signal, in a first display period, and writes a second image based on the image signal in the display panel and turns on at least the second light source, in a second display period.