Curved Reflector Backlight Unit for Uniform Illuminance
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Solution Overview
Problem
Conventional backlight units for LCDs suffer from non-uniform illuminance, leading to degraded image quality due to the Lambertian light emission distribution of LEDs, where most light is emitted at a front part adjacent to the source, resulting in a brighter front and dimmer rear, which complicates the transmission of light to distant areas.
Innovation Solution
Incorporating a reflector with a curved cross-section, such as parabolic or elliptical shapes, adjacent to the light source to totally reflect light emitted laterally, combined with a reflective sheet and diffusion sheets, to convert Lambertian light into parallel or convergent light, ensuring uniform illuminance across the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional backlight unit uses LED light sources with Lambertian emission distribution, then the light source structure is simple, but the illuminance uniformity deteriorates with brighter front and dimmer rear
Solution Approach 1:
The patent applies curved reflectors with parabolic or elliptical cross-sections to redirect light. The curved surfaces reflect Lambertian-emitted light to create parallel or convergent beams, solving the illuminance uniformity problem while maintaining simple LED light sources. The curvature geometry is specifically designed to redirect light from the front toward the rear of the display panel.
Solution Approach 2:
The patent introduces optical elements (curved reflectors, diffusion sheets, light guide plates) that manipulate light in additional spatial dimensions. Rather than relying solely on the inherent Lambertian emission pattern, the system uses multi-dimensional optical path control through reflection, diffusion, and guidance to achieve uniform illuminance distribution across the display panel.
2Device complexity
If light is emitted laterally from the light source, then the light source configuration is simple, but the light transmission to distant areas deteriorates
Solution Approach 1:
Curved reflectors with parabolic or elliptical geometries are positioned adjacent to the light source to capture laterally emitted light and redirect it toward the rear of the display panel. The specific curvature profiles are designed to extend the effective light transmission distance while maintaining a simple light source configuration.
Solution Approach 2:
The patent introduces intermediate optical elements including diffusion sheets and light guide plates that mediate between the light source and the display panel. These intermediaries capture, redirect, and distribute light over extended distances, enabling effective illumination of distant areas without complicating the light source itself.
3Illumination intensity
If diffusion sheets and reflective sheets are added to improve illuminance uniformity, then the illuminance uniformity improves, but the device complexity increases
Solution Approach 1:
The patent combines multiple optical functions into integrated structures. For example, diffusion patterns are incorporated directly into the light guide plate, and reflective surfaces are integrated with the housing structure. This merging approach achieves illuminance uniformity while minimizing the number of separate components and assembly steps.
Solution Approach 2:
The patent designs optical elements to perform multiple functions simultaneously. The light guide plate serves both as a structural support and as a light distribution medium with integrated diffusion patterns. Reflective surfaces serve both as optical elements and as part of the housing structure, reducing overall device complexity despite achieving improved illuminance uniformity.
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 enhances illuminance uniformity by directing light to both front and rear parts, reducing the need for a light guide plate and lowering manufacturing costs, thereby improving the quality of the display image.
Implementation Method 1
a reflector arranged on and under the light source to totally reflect at least a part of light emitted from the light source in a lateral direction
Implementation Method 2
a diffusion sheet arranged on the reflector... to convert Lambertian light into parallel or convergent light, ensuring uniform illuminance
Data Source
AI summary
A backlight unit and a display device having the same are provided. The backlight unit includes a light source, a reflector arranged on and under the light source to totally reflect at least a part of light emitted from the light source in a lateral direction, a reflective sheet arranged under the reflector, and a diffusion sheet arranged on the reflector.