Backlight Unit Beam Profile Changer Weight Reduction
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Solution Overview
Problem
Existing backlight units for liquid crystal displays face challenges in reducing weight while maintaining light use efficiency, as the thickness of the light guide plate is limited by its weight-bearing role.
Innovation Solution
A backlight unit configuration that replaces the traditional light guide plate with a beam profile changer, which includes an incident surface, an emitting surface, and a reflective plate, allowing for uniform luminance without the need for a separate light guide plate, thereby reducing the overall weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the thickness of the light guide plate is reduced to decrease weight, then the weight of the backlight unit is reduced, but the light use efficiency deteriorates
Solution Approach 1:
The patent merges the light guide plate and beam profile changer into a single integrated component. The beam profile changer is positioned adjacent to the light source unit and performs both light guiding and beam shaping functions, eliminating the need for a separate light guide plate and reducing overall component weight while maintaining optical efficiency
Solution Approach 2:
The patent changes the optical parameters of the beam profile changer by incorporating specific refractive index variations and surface curvature designs. The beam profile changer has a refractive index that varies from the incident surface to the emitting surface, enabling efficient light control with reduced thickness
2Weight of moving object
If the thickness of the light guide plate is reduced to decrease weight, then the weight of the backlight unit is reduced, but the uniformity of luminance deteriorates
Solution Approach 1:
The integration of beam profile changer functionality into the light guiding structure ensures that beam shaping and light distribution occur simultaneously, maintaining uniform luminance across the display area while using a thinner, lighter construction
Solution Approach 2:
The beam profile changer incorporates locally varied optical properties including curvature changes and refractive index gradients at different positions. The emitting surface has specific curvature characteristics that differ from the incident surface, enabling localized light control to achieve uniform overall luminance distribution
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
The solution achieves significant weight reduction of the backlight unit while maintaining uniform luminance, as the beam profile changer efficiently collimates and directs light to the liquid crystal display module.
Implementation Method 1
The light guide plate is made of acrylic material having a critical angle of about 42° and a refractive index of about 1.5
Implementation Method 2
light having an azimuth angle equal to or larger than the critical angle is totally reflected and diffused on the entire surface of the light guide plate
Implementation Method 3
The reflective plate is positioned on the lower surface of the light guide plate to reflect leakage light in an inside space of the light guide plate
Implementation Method 4
The diffuser sheet diffuses light traveling through the light guide plate using beads distributed in the diffuser sheet
Implementation Method 5
The prism sheet focuses the light diffused by the diffuser sheet
Data Source
AI summary
A backlight unit is disclosed. The backlight unit includes a light source unit generating light, a beam profile changer at the side of the light source unit, a reflective plate under the beam profile changer, and an optical film positioned on the beam profile changer and the reflective plate. The beam profile changer includes an incident surface facing the light source unit and an emitting surface positioned in a direction parallel to the incident surface. The reflective plate includes a first reflective surface having a first reflective area and a second reflective surface having a second reflective area. The second reflective surface is inclined from an end of the first reflective surface to an upward direction.