Reversed Wedge Light Guide Plate for Uniform Backlight
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Solution Overview
Problem
Conventional planar illumination devices using light guide plates with reduced thickness face limitations in size increase, brightness uniformity, and color temperature adjustment, particularly when using LED light sources, leading to issues with light distribution and efficiency.
Innovation Solution
A planar illumination device featuring a reversed wedge-shaped light guide plate with an inclined surface and a dual LED source configuration, along with a fluorescent member for color temperature adjustment, to enhance light extraction efficiency and brightness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a light guide plate with reduced thickness is used to achieve a thinner backlight unit, then the thickness is reduced, but the light amount uniformity deteriorates
Solution Approach 1:
The light guide plate employs a variable thickness design where the thickness changes in the light incident direction from the light incident surface to the light extraction surface. Specifically, the thickness is smaller near the light incident surface and larger near the light extraction surface, creating local quality variations that compensate for light attenuation and improve uniformity while maintaining overall thinness
Solution Approach 2:
The invention transitions from conventional uniform thickness light guide plates to a three-dimensional variable thickness structure. By introducing thickness variation along the light propagation path (from incident surface to extraction surface), the design optimizes light distribution in the thickness dimension to achieve better uniformity without increasing overall device thickness
2Illumination intensity
If the thickness of the light guide plate is increased to improve light amount uniformity, then the light uniformity is improved, but the backlight unit thickness increases
Solution Approach 1:
Instead of uniformly increasing the entire light guide plate thickness, the invention applies localized thickness variation: the thickness is smaller at the light incident surface region and gradually increases toward the light extraction surface region. This local quality adjustment optimizes light extraction efficiency at different positions without proportionally increasing overall thickness
3Length of stationary object
If a conventional light guide plate is used to achieve a thin profile, then the thickness is reduced, but the device size is limited
Solution Approach 1:
The invention utilizes the thickness dimension strategically by creating a variable thickness profile along the light propagation path. This dimensional optimization allows light to propagate more effectively through the plate, enabling larger emission areas while maintaining thin overall profile
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 allows for a thinner, larger, and more efficient illumination device with improved light use efficiency and adjustable color temperature, ensuring uniform brightness and increased light emission without brightness unevenness.
Implementation Method 1
a light guide plate for diffusing light emitted from a light source to emit illumination light from a light exit surface
Implementation Method 2
a fluorescent member for color temperature adjustment
Data Source
AI summary
It is an object to provide a planar illumination device that is thin and light weight, and can emit uniform illumination light with little brightness unevenness and can be enlarged in size. It is to provide a planar illumination device comprising: a first light source and a second light source which are arranged at predetermined intervals; and a light guide plate which is arranged between the first light source and the second light source and has: a light exit surface; a first light incident surface which is opposed to the first light source and includes a side of the light exit surface; a second light incident surface which is opposed to the second light source and includes an opposite side to the side; and a rear surface which is formed to be opposed to the light exit surface, wherein a cross section on a plane perpendicular to the side, of the rear surface of the light guide plate has a curved line in which a distance from the light exit surface increases with a shift from the first light incident surface and the second light incident surface to a center, an inclined angle relative to the light exit surface reduces with a shift from the first light incident surface or the second light incident surface to the center, and the inclined angle relative to the light exit surface is zero degrees at the center.