Backlight Unit Light Guide Plate Brightness Uniformity
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Solution Overview
Problem
Conventional backlight units experience insufficient brightness uniformity due to light emission near the surface where light enters, despite the use of a low-refractive index layer for improved light utilization efficiency.
Innovation Solution
A backlight unit configuration featuring a light guide plate and a reflective plate bonded via a double-sided pressure-sensitive adhesive film with a low-refractive index layer, where the light source-side end surface of the adhesive film and reflective plate are flush, and light-shielding portions are strategically placed to prevent light leakage, ensuring that light does not enter or exit the space between the low-refractive index layer and the reflective plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a low-refractive index layer is introduced between the light guide plate and reflective plate, then light utilization efficiency is improved, but light leakage occurs near the light entry surface causing insufficient brightness uniformity
Solution Approach 1:
The patent segments the bonding interface between the light guide plate and reflective plate by introducing a double-sided pressure-sensitive adhesive film with multiple layers. This includes a first pressure-sensitive adhesive layer, a low-refractive index layer, and a second pressure-sensitive adhesive layer, thereby separating the bonding function from the optical function and preventing light leakage while maintaining light utilization efficiency.
Solution Approach 2:
The double-sided pressure-sensitive adhesive film acts as an intermediary between the light guide plate and reflective plate. The low-refractive index layer within this intermediary structure prevents light from entering the bonding interface, while still allowing the light guide function to operate effectively, thus resolving the contradiction between light utilization and light leakage prevention.
2Device complexity
If the light guide plate and reflective plate are simply laminated with pressure-sensitive adhesive, then device complexity is reduced, but brightness uniformity is insufficient due to light emission near the entry surface
Solution Approach 1:
The patent applies local quality by making the adhesive film have different properties in different regions. The low-refractive index layer is positioned specifically at the light entry region to prevent light leakage, while other regions maintain standard adhesive properties. This localized modification improves brightness uniformity without significantly increasing overall device complexity.
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 significantly suppresses light leakage near the surface that light enters, resulting in a backlight unit with enhanced brightness uniformity.
Implementation Method 1
a low-refractive index layer improves light utilization efficiency
Implementation Method 2
bonded to each other via a double-sided pressure-sensitive adhesive film
Data Source
AI summary
A backlight unit includes: a light source; a light guide plate arranged to face the light source, having an end surface that light from the light source enters; and an emitting surface from which the entered light is emitted; a reflective plate bonded to a back surface side of the light guide plate via a double-sided pressure-sensitive adhesive film; and a casing having a front portion and a back portion, the casing configured to store the light source, the light guide plate, and the reflective plate. The backlight unit is configured so that light from the light source is free from entering a space between the low-refractive index layer and the reflective plate, or so that light that has entered the space between the low-refractive index layer and the reflective plate from a light source is free from being emitted from the emitting surface of the light guide plate.