Planar Illumination Device Fixing Members for Reliability
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Solution Overview
Problem
Downsizing fixing members in edge-light planar illumination devices can lead to insufficient fixing force, affecting the reliability and luminance distribution of the device.
Innovation Solution
A planar illumination device design that includes two fixing members, one between the light guide plate and the substrate, and another opposite to it across the light guide plate, with a comb-shaped second fixing member having protrusions and cutouts to increase the bonding area and prevent light absorption, ensuring proper alignment and increased fixing force while maintaining light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If fixing members are downsized to meet narrower frame demands, then device size is reduced, but bonding area decreases leading to insufficient fixing force
Solution Approach 1:
The patent divides the fixing function into two separate fixing members: a first fixing member that bonds the light guide plate to the substrate, and a second fixing member that bonds the light guide plate to the LED. This segmentation allows each fixing member to be optimized independently, with the second fixing member specifically positioned to provide strong bonding between the light guide plate and LED without interfering with light emission, thereby resolving the contradiction between device downsizing and maintaining sufficient fixing force.
2Device complexity
If fixing members are downsized, then device complexity is reduced, but reliability of fixing deteriorates
Solution Approach 1:
The patent introduces a substrate as an intermediary component between the LED and the light guide plate. The first fixing member bonds the light guide plate to this substrate, while the second fixing member bonds the light guide plate to the LED. This intermediary structure allows for reliable fixing without requiring complex direct bonding between the LED and light guide plate, thus maintaining reliability while managing device complexity.
3Illumination intensity
If optical axes of LED and light guide plate are aligned, then luminance distribution is improved, but fixing alignment precision requirements increase
Solution Approach 1:
The patent designs the second fixing member to automatically align the optical axis of the LED with the optical axis of the light guide plate during the bonding process. The fixing member's structure includes positioning features that guide the LED into the correct orientation, allowing the assembly to self-align without requiring high-precision external alignment equipment. This reduces manufacturing precision requirements while ensuring proper optical axis alignment for uniform luminance distribution.
Data Source
AI summary
A planar illumination device according to an embodiment includes a light guide plate, a substrate, a light source, a first fixing member, and a second fixing member. The light guide plate outputs, from a principal surface, light entering from a side surface. The substrate is disposed substantially in parallel with the principal surface of the light guide plate. The light source is provided on the substrate in a manner facing the side surface of the light guide plate. The light source has a light-emitting surface that outputs the light incident on the side surface. The first fixing member is disposed between the light guide plate and the substrate and fixes the light guide plate to the substrate. The second fixing member is disposed opposite to the first fixing member across the light guide plate and fixes the light guide plate to the light source.