Backlight Unit Frame Protrusions for Positional Stability

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Solution Overview

Problem

The existing backlight unit structures for liquid crystal display devices suffer from relative positional displacements among the inner frame, light guide plate, and outer frame, leading to instability in the display area, despite providing ease of assembly through clearances.

Innovation Solution

The proposed solution involves a backlight unit design with inner and outer frames featuring protrusions that project towards each other, strategically located to stabilize the light guide plate within the inner frame and the inner frame within the outer frame, ensuring precise positioning and reducing positional displacements while maintaining ease of assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If clearances are provided between the inner frame and light guide plate, and between the inner frame and outer frame, then the ease of assembling is improved, but positional displacements occur among the members

Engineering Contradiction:
Improveease of assemblingVSAvoidpositional displacement
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The frame structure is segmented by adding protrusions that divide the continuous frame into sections with localized positioning functions. The protrusions act as discrete positioning elements that segment the assembly process, guiding each component into its correct position while maintaining overall structural integrity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Protrusions are introduced as intermediary elements between the frame components and the light guide plate. These protrusions serve as mediators that transmit positioning forces and constraints, enabling precise positioning without requiring tight clearances between the main frame structures.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If clearances are provided to enable easy assembly, then the ease of operation is improved, but the stability of the display area deteriorates

Engineering Contradiction:
Improveease of assemblingVSAvoidstability of display area
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The protrusions are pre-formed on the frame structures before assembly, creating preliminary positioning features that guide the components into their correct relative positions during assembly. This preliminary action ensures stable positioning is achieved automatically as part of the assembly process, without requiring post-assembly adjustments.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If the inner frame is made rigid to suppress positional displacement, then the manufacturing precision is improved, but the ease of assembling deteriorates

Engineering Contradiction:
Improvepositional accuracyVSAvoidease of assembling
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The frame structure incorporates dynamic characteristics by allowing localized deformation at specific regions (opposite to protrusions) while maintaining rigidity at positioning-critical regions. This dynamic design enables the frame to flex slightly during assembly to accommodate the protrusions, then stabilizes into a precise final position, combining ease of assembly with positioning accuracy.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2442177B1Backlight unit and liquid crystal display device
Publication Date: 2013.06.19 HITACHI DISPLAYS LTD
  • EP2442177B1 patent drawingFigure 1
  • EP2442177B1 patent drawingFigure 2
  • EP2442177B1 patent drawingFigure 3

AI summary

A backlight unit includes a light guide plate (20), an inner frame (30) that surrounds an outer periphery of the light guide plate (20), and an outer frame (40) that surrounds an outer periphery of the inner frame (30). An inner periphery of the inner frame (30) is formed with an inner protrusion (35) that projects toward the outer periphery of the light guide plate (20). The outer periphery of the inner frame (30) is formed with an outer protrusion that projects toward an inner periphery of the outer frame (40). The inner protrusion (35) and the outer protrusion are located on opposite sides of a wall part that is one side part (33) of the inner frame (30), and arranged at a distance from each other in a longitudinal direction of the wall part of the inner frame (30). According to the backlight unit, relative positional displacement of members can be suppressed while ensuring the ease of assembling.