Light Guide Convex Portions for Display Illumination Uniformity
Solution Overview
Problem
Current illumination devices for display devices, such as liquid crystal display devices, face challenges in achieving high emission efficiency due to limitations in light propagation and diffusion within the light guide, leading to suboptimal luminance and uneven light distribution.
Innovation Solution
The illumination device incorporates a light guide with convex portions on its second main surface and strategically positioned light source elements, along with a reflector, to optimize light entry and reflection, ensuring that the incident angle of light satisfies the condition ((β0+δ)/3) < θ < ((β0−δ)/2, which enhances light emission efficiency and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light propagates through a conventional light guide without convex portions, then the structure is simple, but light emission efficiency and luminance uniformity are insufficient
Solution Approach 1:
The light guide incorporates convex portions (curved surface structures) on its lower surface to diffract and reflect light. These curved surfaces modify the propagation path of light, improving emission efficiency and luminance uniformity without significantly complicating the manufacturing process, as the convex portions can be formed through standard molding techniques.
2Device complexity
If light propagates through a conventional light guide without optimized reflection, then the structure is simple, but luminance uniformity across the display panel is poor
Solution Approach 1:
The light guide features localized convex portions positioned at specific regions (e.g., closer to or farther from the light source) to address local luminance variations. This local modification approach improves overall luminance uniformity without requiring complete structural redesign of the entire light guide system.
Solution Approach 2:
The lower surface of the light guide is divided into multiple regions with different convex portion configurations. By segmenting the light guide surface and applying different geometric features to different segments, the patent achieves more uniform light distribution across the display panel while maintaining reasonable structural complexity.
3Productivity
If convex portions are added to the light guide to improve light diffusion, then light emission efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The convex portions on the light guide serve multiple functions simultaneously: they act as diffusers to scatter light, as reflectors to redirect light paths, and as structural features that can be integrated into the existing light guide molding process. This multi-functionality approach improves light emission efficiency without proportionally increasing manufacturing complexity.
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 configuration significantly improves light emission efficiency and luminance uniformity, enabling high-luminance image display by effectively diffusing and reflecting light within the light guide.
Implementation Method 1
the entering light propagates inside the light guide while being reflected on the first main surface and the second main surface
Implementation Method 2
a plurality of convex portions provided on the second main surface of the light guide
Data Source
AI summary
According to one embodiment, an illumination device includes a light guide including a first main surface, a second main surface, a first side surface, and a second side surface, a plurality of convex portions provided on the second main surface, and a first light source element and a second light source element opposing the first side surface and the second side surface, respectively, and when an incident angle of a main ray of the light propagating in the light guide is expressed by θ, a diffusion angle of the light is δ, an angle of the convex portion of the light guide is α, a critical angle of the light guide is θc, and an angle which satisfies (90°−θc) is β0, a relationship: ((β0+δ)/3)<θ<((β0−δ)/2) is satisfied.