Edge-Lit Illumination Device With Extended Light Guide Portion
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Solution Overview
Problem
In edge-light illumination devices for liquid crystal displays, the corner portions of the light guide plate experience low luminance due to the directional emission of LEDs, leading to an increased non-display region size when attempting to address this issue by aligning LEDs with oblique end surfaces, which hinders the realization of a narrow picture-frame design.
Innovation Solution
An illumination device featuring a light source row of first LEDs aligned in a row with intervals, accompanied by second LEDs positioned at both ends to cover an extended portion of the light guide member, ensuring uniform light distribution and reducing the non-display region size by supplementing light to corner areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LEDs are disposed to face corner portions of the light guide plate to improve luminance at corner portions, then luminance uniformity is improved, but the size of the non-display region increases
Solution Approach 1:
The light guide member extends in the thickness direction (Z-axis) to form an extended portion that protrudes from the light-incident surface. This dimensional extension allows second LEDs to be disposed at corner portions without increasing the planar footprint, thereby improving corner luminance while maintaining a compact non-display region boundary.
Solution Approach 2:
The extended portion of the light guide member is nested within the non-display region boundary, allowing the second LEDs to be positioned at corner portions while remaining contained within the allowable non-display area. This nested configuration enables corner illumination without expanding the overall device footprint.
2Use of energy by moving object
If LEDs emit light in a predetermined spread angle direction, then light emission efficiency is improved, but light distribution uniformity deteriorates
Solution Approach 1:
Different regions of the light guide member receive light from different LED configurations: the light-guide main portion receives light from first LEDs with predetermined spread angles for efficient emission, while the extended portion at corner portions receives light from second LEDs specifically oriented to illuminate corner areas, achieving local optimization of both efficiency and uniformity.
Solution Approach 2:
The illumination system is segmented into two distinct LED groups: first LEDs arranged in a row for the light-guide main portion with optimized spread angle for efficiency, and second LEDs at corner portions for targeted corner illumination. This segmentation allows each group to be optimized for its specific function while collectively achieving uniform light 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
This configuration effectively suppresses low luminance at the ends of the light source row, allowing for a narrower non-display region and improved light distribution across the display panel, enabling a more compact and uniformly illuminated display.
Implementation Method 1
a light guide member 19... having a light-guide main portion 191 in a plate shape including a light-incident surface 191c which is an end surface facing the first light-emitting portion and on which light from the first light-emitting portion is incident and a light-emitting surface 191a which is a plate surface on a front side and from which light entering the light-guide main portion 191 from the light-incident surface 191c is externally emitted
Data Source
AI summary
An illumination device includes a light source row made up of multiple first light sources, each emitting light in the same direction and being aligned in a row with intervals maintained therebetween; a light guide member having a light-guide main portion in a plate shape including a light-incident surface which faces a first light-emitting portion and on which light from the first light-emitting portion is incident and a light-emitting surface from which light enters from the light-incident surface is externally emitted, and an extended portion in a plate shape thinner in thickness than the light-guide main portion and extending toward an outer side from part of the end surface of the light-guide main portion to cover the light source row from the front side; and multiple second light sources having a second light-emitting portion that emits light toward the extended portion and being disposed aligned in the row along with the light source row at both ends of the light source row to be covered by the extended portion.