Edge-lit Backlight Unit Extending Portion for Narrow Frame Bright Lines

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Solution Overview

Problem

Edge bright lines at large viewing angles in display devices with edge-lit backlight units are exacerbated by the structural limitations of the rubber frame and light guide plate, particularly in narrow frame designs, affecting the display's visual quality.

Innovation Solution

The edge-lit backlight unit incorporates an extending portion on the light guide plate that moves its edge outward, overlapping with the rubber frame, which reduces or eliminates edge bright lines by altering the light leakage pattern and improving the display's visibility angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the light guide plate edge is positioned close to the visible region to achieve narrow frame structure, then the device compactness is improved, but edge bright lines appear at large viewing angles

Engineering Contradiction:
Improveframe widthVSAvoidedge bright lines
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a rubber frame as an intermediary component positioned between the light guide plate edge and the visible region. This rubber frame absorbs and scatters the leaked light that would otherwise create edge bright lines, while allowing the light guide plate edge to remain close to the visible region for narrow frame structure. The rubber frame acts as a mediator that resolves the conflict between compactness and visual quality.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the rubber frame width is increased to block edge light leakage, then edge bright lines are reduced, but the device complexity and space consumption increase

Engineering Contradiction:
Improveedge bright linesVSAvoidrubber frame width
Core Design Contradiction:
Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The patent optimizes the rubber frame width parameter to a specific range that is sufficient to block edge light leakage but not excessively wide. By carefully selecting and adjusting this dimensional parameter, the solution achieves effective suppression of edge bright lines while maintaining a compact overall device structure and avoiding unnecessary space consumption.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If the light guide plate edge is moved outward to reduce edge bright lines, then viewing angle performance is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveedge bright linesVSAvoidedge positioning accuracy
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The rubber frame serves as a positioning intermediary that simplifies the manufacturing process. Instead of requiring precise positioning of the light guide plate edge relative to the visible region, the rubber frame provides a tolerant interface that absorbs positioning variations. This mediator approach reduces the stringency of manufacturing precision requirements while still achieving the goal of minimizing edge bright lines.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3422058B1Edge-lit backlight unit and display device
Publication Date: 2021.04.07 BOE TECHNOLOGY GROUP CO LTD
  • EP3422058B1 patent drawingFigure 1~3a
  • EP3422058B1 patent drawingFigure 3b~6a
  • EP3422058B1 patent drawingFigure 6b~7b

AI summary

An edge-lit backlight unit and a display device are provided. The backlight unit includes a light guide plate (2) and a rubber frame (3), wherein, the light guide plate (2) includes a main body portion (21), the main body portion (21) is of a flat plate structure and includes a first main surface (23) and a second main surface (24) which are opposite to each other and a lateral surface, and the lateral surface includes a first lateral surface portion (28) used as a light incident side and a second lateral surface portion (25) outside the first lateral surface portion (28); the light guide plate (2) further includes an extending portion (22) extending outwards from at least a part of the second lateral surface portion (25) of the main body portion (21), and a thickness of the extending portion (22) is smaller than that of the main body portion (21); and at least a part of the rubber frame (3) and the second lateral surface portion (25) of the main body portion (21) are oppositely arranged at an interval and the at least a part of the rubber frame (3) is at least partially overlapped with the extending portion in the thickness direction of the main body portion. With the above backlight unit, the phenomenon of the edge bright lines at a large viewing angle of a display device can be effectively relieved.