Backlight Optical Sheet Slits for Impact Resistance
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Solution Overview
Problem
The existing backlight units for liquid crystal display (LCD) devices lack a structural element to absorb impact forces, leading to potential cracking of optical sheets during delivery, which can result in defects such as cracks, detachment, wrinkling, or denting, and degrade display quality due to foreign material intrusion.
Innovation Solution
Incorporating slits between the edges of the hooks and elliptical holes in the optical sheets of the backlight unit to absorb and disperse external impact forces, preventing stress concentration and sheet damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the optical sheets are fixed using hooks with elliptical holes engaging protrusions, then the optical sheets are securely positioned, but the hooks become weak points that concentrate stress under impact force causing cracks
Solution Approach 1:
The patent divides the continuous material of the optical sheet into separate segments by introducing slits that extend from the elliptical hole toward the hook edge. This segmentation allows stress to be distributed across multiple smaller sections rather than concentrating at a single point, preventing crack propagation while maintaining the positioning function of the hook-protrusion engagement.
Solution Approach 2:
The patent applies local quality by creating slits only in specific locations where stress concentration occurs (near the engagement point of the hook and protrusion), rather than uniformly throughout the entire optical sheet. This localized modification provides crack resistance exactly where needed while preserving the overall structural integrity and positioning stability of the sheet.
2Length of moving object
If the thickness of the rib portion is reduced to accommodate smaller bezel width, then the device size is reduced, but the impact resistance of the hooks is weakened increasing crack occurrence
Solution Approach 1:
By introducing slits that segment the material around the elliptical hole, the patent creates multiple stress distribution paths. This allows the rib portion to maintain adequate thickness for strength while the slits provide additional crack resistance, effectively decoupling the relationship between reduced thickness and increased fragility.
Solution Approach 2:
The slits act as pre-designed stress relief features that cushion against impact forces before cracks can develop. By incorporating these slits in advance during manufacturing, the optical sheet is prepared to absorb and distribute impact energy, compensating for the reduced thickness of the rib portion without requiring increased material usage.
3Manufacturing precision
If point contacts or narrow contact surfaces are used between hooks and protrusions, then the positioning is precise, but stress concentrates at contact points causing cracks under impact
Solution Approach 1:
The slits divide the material around the contact point into separate zones, preventing stress from concentrating at the narrow contact surface between the hook and protrusion. This segmentation maintains precise positioning through the engagement geometry while distributing impact stress across multiple smaller areas rather than a single concentrated point.
Solution Approach 2:
The patent applies local quality by modifying only the immediate vicinity of the contact point with slits, preserving the precise engagement geometry of the hook and protrusion while locally enhancing stress distribution. The slits are positioned to provide crack resistance without interfering with the positioning function.
Data Source
AI summary
The disclosure relates to the backlight unit for preventing the optical sheet from cracking and the liquid crystal display using the backlight unit. The backlight unit comprises a light having a plurality of light sources; a bottom cover housing the light and having a first protrusion; a support side engaging to both open ends of the bottom cover to support the light and having a second protrusion; an optical sheet disposing on the light and including a first hook having a first elliptical hole for inserting the first protrusion and a second hook having a second elliptical hole for inserting the second protrusion; and a first slit between an edge of the first hook and the first elliptical hole within the first hook, and a second slit between an edge of the second hook and the second elliptical hole within the second hook.