Light Guide Plate Irregularities for Backlight Brightness Uniformity
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Solution Overview
Problem
In liquid crystal display devices with edge-lit backlight units, the intimate contact between the reflective sheet and the light guide plate leads to light absorption, causing uneven brightness distribution, and existing solutions like roughening the rear surface to reduce contact alter the convex or concave portion shapes, affecting light convergence and efficiency.
Innovation Solution
The display device features a light guide plate with irregularities on the front surface, comprising a combination of first and second convex or concave portions, and a reflective sheet with enhanced specular reflectance, allowing efficient light exit and convergence without altering brightness distribution due to intimate contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective sheet with high reflectance ratio is used to return light that passes through the rear surface, then light efficiency is improved, but light that is supposed to be reflected at the interface on the rear surface is absorbed in the reflective sheet due to intimate contact
Solution Approach 1:
The patent applies preliminary action by pre-forming convex portions and concave portions on the rear surface of the light guide plate before assembling the reflective sheet. These irregularities are created in advance to prevent intimate contact between the reflective sheet and the light guide plate, thereby preventing light absorption issues before they occur during operation.
Solution Approach 2:
The patent applies local quality by creating specific convex portions and concave portions at specific locations on the rear surface of the light guide plate. These localized irregularities are strategically positioned to control light reflection and prevent intimate contact with the reflective sheet, while maintaining overall light efficiency.
2Object-generated harmful factors
If the rear surface is roughed by blasting to reduce intimate contact with the reflective sheet, then light absorption is reduced, but the shapes of the convex portions or concave portions are changed and brightness distribution is altered
Solution Approach 1:
Instead of applying roughing treatment after forming the convex and concave portions, the patent uses preliminary action by directly forming the desired convex and concave portion shapes during the molding process. This avoids subsequent roughing treatments that would alter the precise shapes and brightness distribution.
Solution Approach 2:
The patent replaces the mechanical roughing process (blasting) with a molding process that directly forms the required surface irregularities. This substitution eliminates the need for post-molding roughing treatments while achieving the same goal of preventing intimate contact with the reflective sheet.
3Productivity
If irregularities are formed on the front surface to improve light exit efficiency, then light convergence is achieved, but the complexity of the light guide plate structure increases
Solution Approach 1:
The patent merges the functions of light reflection control and light exit optimization into a single integrated structure. The convex portions and concave portions on the rear surface serve dual purposes: controlling light reflection to prevent reflective sheet contact and guiding light for efficient exit through the front surface.
Solution Approach 2:
The irregularities (convex portions and concave portions) on the rear surface serve multiple functions simultaneously: they prevent intimate contact with the reflective sheet, control light reflection paths, and guide light toward the front surface for efficient exit. This multi-functionality reduces the need for additional separate components.
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 enables efficient light exit and convergence while maintaining consistent brightness distribution, improving light efficiency by up to 15% compared to conventional designs, as demonstrated by the enhanced specular reflector and roughened rear surface configurations.
Implementation Method 1
the light guide plate being configured to internally reflect light entering from the edge surface to cause planar light emission from the front surface
Implementation Method 2
a reflective sheet arranged so as to be opposed to the rear surface of the light guide plate
Data Source
AI summary
Provided is a display device including: a light guide plate arranged so that an edge surface thereof is opposed to a light source, the light guide plate being configured to internally reflect light entering from the edge surface to cause planar light emission from a front surface of the light guide plate; and a reflective sheet arranged so as to be opposed to a rear surface of the light guide plate. Irregularities are formed on the front surface. The irregularities are formed to have a shape of a combination of first convex portions and second convex portions, each of the first convex portions including a first ridge line which continuously extends along a first direction corresponding to a light traveling direction, each of the second convex portions including a second ridge line which continuously extends along a second direction intersecting the first direction.