Laser Groove Formation in Light Guide Plates for LCD Illumination
Solution Overview
Problem
The variability in thickness of translucent resin light guide plates affects the precision of laser beam focusing, leading to inconsistent groove formation and quality issues in light guide plates used in liquid crystal display devices.
Innovation Solution
A manufacturing method involving the formation of second grooves in the outer circumferential region of the light guide plate, followed by inspection and adjustment of laser irradiation conditions, allows for the precise formation of first grooves with appropriate dimensions, regardless of plate thickness variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a groove is formed with a laser beam on the light guide plate surface, then the illumination light emitting intensity is enhanced, but the groove dimensions and depth become inconsistent due to thickness variation of the light guide plate
Solution Approach 1:
The patent applies preliminary action by forming a groove in the light guide plate before mounting it on the display device. This groove serves as a light-trapping structure that prevents light from escaping directly at the edge, thereby enhancing illumination intensity. The groove is formed at a predetermined position and depth based on the nominal thickness of the light guide plate, allowing the enhancement effect to be achieved while accommodating reasonable thickness variations through the preliminary structuring of the light path.
2Adaptability or versatility
If the light guide plate thickness varies for each plate, then the relationship between the surface and laser focus position varies, but this causes quality variation in the formed grooves
Solution Approach 1:
The patent addresses thickness variation by establishing specific parameter ranges for the groove depth relative to the light guide plate thickness. The groove depth is defined as 0.01 to 0.05 times the plate thickness, creating a scalable parameter relationship that adapts to different thicknesses while maintaining consistent optical performance. This parameter-based approach allows the same manufacturing process to produce quality grooves across light guide plates with varying thicknesses.
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 method enhances the quality of light guide plates by ensuring consistent groove dimensions and depths, improving illumination uniformity and reducing unnecessary scattering reflections.
Implementation Method 1
a groove is formed with a laser beam on a surface opposite to the light incident surface in the light guide plate
Implementation Method 2
When a groove is formed with a laser beam as in JP-A-2008-20888, the light guide plate is displaced while the light guide plate is irradiated with a laser beam
Implementation Method 3
an opposite surface facing the light outgoing surface of the light guide plate is provided with a scattering reflection region
Implementation Method 4
a plurality of groove arrays including a plurality of first grooves linearly extending in a first direction are provided in a parallel manner
Data Source
AI summary
When first grooves are formed by irradiating a lower surface facing a light outgoing surface of a light guide plate for an illuminating device with laser beams, an outer circumferential region is firstly irradiated with the laser beams to form second grooves. Then, the second grooves are inspected. Next, irradiation conditions of the laser beams are adjusted based on an inspection result of the second grooves, irradiation positions of the laser beams are linearly displaced from formation positions of the second grooves, and formation of the first grooves in the scattering reflection region is then started.