Backlight Unit Local Dimming Tinting Control
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Solution Overview
Problem
In image display devices with backlight units that incorporate wavelength conversion members and local dimming control, a phenomenon of tinting occurs in darkly displayed areas, where the chromatic coordinates of white light deviate from those in brightly displayed areas, leading to reduced image quality.
Innovation Solution
A backlight unit is designed with a light source unit and a wavelength conversion member, where the wavelength conversion member includes fluorescent bodies emitting green and red light, and the light source unit allocates light sources with different emission maximum wavelengths to areas, allowing independent control of light emission intensities to adjust for leaked light influences, using a multi-wavelength heterogeneous light source group to minimize tinting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If local dimming control is implemented to reduce backlight brightness in dark areas, then power consumption is reduced and contrast is enhanced, but tinting occurs in darkly displayed areas causing chromatic coordinates to deviate
Solution Approach 1:
The backlight unit is divided into multiple independently controllable light source groups corresponding to different display areas. Each light source group can be controlled separately to emit light with different intensities and wavelength compositions, allowing precise chromaticity management in each local region while implementing dimming control.
Solution Approach 2:
Different wavelength composition light sources are allocated to different areas based on local requirements. In darkly displayed areas, the light source composition and intensity are specifically adjusted to compensate for potential tinting, ensuring that each local region maintains accurate chromatic coordinates according to its display needs.
2Reliability
If local dimming control is implemented to enhance contrast by locally reducing backlight brightness, then image contrast is improved, but yellowish tints appear in dark areas reducing image quality
Solution Approach 1:
The backlight unit is segmented into multiple independently controllable light source groups, each capable of emitting light with different wavelength compositions. This allows different areas to have optimized light characteristics - high brightness areas use standard composition while dark areas use adjusted composition to prevent yellowish tints and maintain contrast simultaneously.
Solution Approach 2:
The wavelength composition and intensity parameters of light sources are dynamically adjusted based on the display content and local brightness requirements. By changing these parameters locally, the system maintains accurate chromatic coordinates in dark areas while still achieving the contrast enhancement benefits of local dimming.
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 configuration effectively reduces tinting in darkly displayed areas by adjusting the light emission intensities of different wavelength light sources, maintaining accurate chromatic coordinates and enhancing image quality by preventing yellowish tints.
Implementation Method 1
a wavelength conversion member (including at least a wavelength conversion layer) that includes a fluorescent body excited by the light emitted from the light source and emits fluorescence
Data Source
AI summary
The backlight unit includes a light source unit, and a wavelength conversion member disposed on an optical path of light emitted from the light source unit. The light source unit includes a light source allocated to each of the areas, a control of the backlight brightness for each area is performed by controlling a light emission intensity of each light source allocated to each area independently of a light emission intensity of a light source allocated to a different area, and a light source allocated to at least one area includes a light source group including two or more kinds of light sources having different light emission maximum wavelengths, and a light emission intensity of at least one kind of light source included in the light source group is capable of being controlled independently of a light emission intensity of a different light source included in the light source group.