Optical Sheet Printed Dots Sticking Prevention
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Solution Overview
Problem
Conventional edge-lit backlight units face issues with scratches on the optical waveguide plate due to protruding beads in the sticking preventive layer, leading to non-uniform luminance and potential detachment, which causes further scratches and adhesion problems.
Innovation Solution
An optical sheet with a sticking preventive portion comprising printed dots on its back face, which prevents sticking to the optical waveguide plate and inhibits scratches by scattering the dots over the surface, ensuring effective adhesion and preventing bead detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sticking preventive layer with protruding beads is used to prevent adhesion, then sticking prevention is achieved, but scratches are generated on the optical waveguide plate
Solution Approach 1:
The patent replaces durable acrylic resin beads with inexpensive pigment particles that are intentionally designed to be removed during processing. These pigment particles serve their sticking prevention function temporarily and are then discarded, eliminating the scratch problem caused by persistent hard beads
Solution Approach 2:
The patent changes the material parameter from hard acrylic resin beads to soft pigment particles, and controls the particle size within a specific range (0.1-10 μm). This parameter change allows the particles to prevent sticking while being gentle enough not to scratch the optical waveguide plate surface
2Reliability
If acrylic resin beads are used for sticking prevention, then adhesion is prevented, but the beads may detach and cause further scratches
Solution Approach 1:
The pigment particles are designed as single-use elements that perform their sticking prevention function during assembly and processing, then are easily removed and discarded. This eliminates the problem of bead detachment causing scratches, as the particles are meant to be temporary
Solution Approach 2:
The sticking preventive layer uses a composite formulation combining pigment particles with a binder resin. This composite structure provides adequate adhesion prevention while allowing the particles to be easily removed after serving their purpose, preventing detachment issues
3Reliability
If a sticking preventive layer is applied to prevent moire patterns, then adhesion is prevented, but uniform luminance is compromised due to scratches
Solution Approach 1:
By using removable pigment particles instead of permanent beads, the surface remains intact after processing. This preserves the optical waveguide plate's ability to transmit light uniformly, maintaining luminance quality while still preventing sticking during assembly
Solution Approach 2:
The patent optimizes particle size parameters (0.1-10 μm) to ensure the sticking preventive layer does not create surface irregularities that would scatter light. This parameter control maintains both sticking prevention and uniform luminance output
Data Source
AI summary
An optical sheet includes: a transparent substrate sheet; and a sticking preventive portion provided on the back face of the transparent substrate sheet. The sticking preventive portion includes a plurality of printed dots. The average diameter of the printed dots is preferably no less than 1 μm and no greater than 200 μm. The ratio of the average height to the average diameter of the printed dots is preferably no less than 1/100 and no greater than 1. The printed dot preferably has a hemisphere-like shape having a height less than a diameter. The arrangement density of the printed dots on the back face of the substrate sheet is preferably no less than 10 dots/mm2 and no greater than 2,500 dots/mm2. A principal component of the printed dots is preferably is preferably an acrylic resin, a urethane resin or an acrylic urethane resin.