Backlight Frame Embedded Block Thermal Expansion Management

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Solution Overview

Problem

Backlight sources in liquid crystal displays face challenges during high-temperature and high-humidity tests, where the optical film sheet tends to wrinkle due to differential expansion between the light guiding plate and the frame, leading to defects that hinder product reliability.

Innovation Solution

A backlight source design featuring a frame, optical film sheet, and an embedded block with a higher coefficient of volume expansion, where the optical film sheet is laminated on the light guiding plate, and the embedded block is positioned within a groove in a transverse protrusion, allowing for expansion and preventing excessive squeeze, thus avoiding wrinkles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the light guiding plate and frame are rigidly fixed together, then structural stability is improved, but the optical film sheet wrinkles during high-temperature and high-humidity tests due to differential thermal expansion

Engineering Contradiction:

Improvestructural stabilityVSAvoidreliability under thermal stress

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The frame is divided into multiple segments by introducing embedded blocks with grooves, creating a segmented structure that allows independent movement of each segment. This segmentation enables the frame to accommodate differential thermal expansion between the light guiding plate and frame without causing wrinkles in the optical film sheet, while still maintaining overall structural stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the thermal expansion parameter by selecting materials for the embedded blocks that have different coefficients of thermal expansion compared to the frame material. This parameter change allows the embedded blocks to expand or contract at different rates than the frame, absorbing thermal stress and preventing wrinkles in the optical film sheet during temperature variations.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the optical film sheet is tightly laminated on the light guiding plate, then optical uniformity is improved, but the film becomes prone to wrinkles and defects during thermal testing

Engineering Contradiction:

Improveoptical uniformityVSAvoidwrinkles and defects under thermal stress

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The embedded blocks with grooves provide beforehand cushioning by creating expansion spaces that accommodate thermal expansion before it can transmit stress to the optical film sheet. This prior cushioning prevents the differential expansion from causing wrinkles or defects in the tightly laminated film during high-temperature and high-humidity tests.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If the frame structure is simplified without embedded blocks, then manufacturing complexity is reduced, but the backlight source fails reliability tests due to optical film sheet wrinkles

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidpass rate of reliability tests

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The embedded blocks are nested within the frame structure, with grooves that receive and secure the light guiding plate. This nesting approach integrates the thermal expansion compensation function directly into the existing frame structure without requiring separate components or complex assembly procedures, thereby maintaining ease of manufacture while improving reliability.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 design prevents wrinkles in the optical film sheet during high-temperature and high-humidity tests, ensuring the backlight source passes reliability tests without defects, such as abrasion or foreign substances, and maintains structural integrity.

Implementation Method 1

a coefficient of volume expansion of the embedded block is greater than a coefficient of volume expansion of the frame

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9658386B2Backlight source and display device

Publication Date: 2017.05.23 BOE TECHNOLOGY GROUP CO LTD

AI summary

A backlight source and a display device are disclosed. The backlight source includes a frame, an optical film sheet, a light guiding plate and an embedded block. The coefficient of volume expansion of the embedded block is greater than the coefficient of volume expansion of the frame; the frame has a first transverse protrusion formed at a side in proximity to a light guiding plate, a bottom surface of the first transverse protrusion is attached to the light guiding plate by pressing, and the bottom surface has a groove provided therein, in which the embedded block is arranged.