Electronic Paper Display Lighting Structure to Eliminate Bezel Ghosting
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Solution Overview
Problem
Current electronic paper displays suffer from ghosting near the black bezel due to similar refractive indices of the optical adhesive layer and light guide plate, leading to uneven refraction and reflection, which affects display appearance and viewability.
Innovation Solution
Incorporating a low-refractive-index transparent resin layer between the surface cover plate and lighting module, with a refractive index less than 1.40, to form a complete reflection interface and eliminate ghosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a first optical adhesive layer with refractive index similar to the light guide plate is used to glue the surface cover plate and lighting module, then the bonding strength is sufficient, but light is partially refracted to the adhesive layer and surface cover plate, causing uneven refraction and reflection that produces ghosting on the display
Solution Approach 1:
A second optical adhesive layer with lower refractive index (1.30-1.40) is introduced as an intermediary between the first optical adhesive layer and the light guide plate. This intermediate layer has a refractive index that creates a gradual transition, reducing the refraction of light at the interface and eliminating the ghosting effect while maintaining adequate bonding strength through the combined adhesive layers
Solution Approach 2:
The refractive index parameter of the adhesive system is changed by introducing a second adhesive layer with specifically controlled lower refractive index (1.30-1.40) compared to the first adhesive layer (1.45-1.55). This parameter change optimizes light transmission characteristics and eliminates unwanted refraction effects
2Stability of the object's composition
If the light guide plate and black bezel are tightly glued together by the first optical adhesive layer, then the structural integrity is maintained, but the similar refractive indices cause light to be affected by the black bezel, creating dark or bright light texture that reduces viewability
Solution Approach 1:
The second optical adhesive layer serves as an optical intermediary between the light guide plate and the black bezel area, creating a refractive index gradient that prevents light from being abruptly affected by the black bezel edge, thereby eliminating the dark or bright light texture while maintaining the tight bonding for structural integrity
Solution Approach 2:
By changing the refractive index parameter of the adhesive system through the second adhesive layer, the light propagation characteristics are optimized to prevent uneven illumination near the black bezel, ensuring uniform display brightness across the entire display area
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
The low-refractive-index transparent resin layer ensures even illumination by preventing light from being affected by the black bezel, enhancing display quality and appearance.
Implementation Method 1
The refractive index of the first optical adhesive layer 40 is approximately between 1.47 and 1.51, and the refractive index of the light guide plate 21 (acrylic) is about 1.491. The both are very similar in refractive index, so the light from the point lights 22 emitted into a lateral side of the light guide plate 21 will be partially refracted to the first optical adhesive layer 40 and surface cover plate 30
Implementation Method 2
By the low-refractive-index transparent resin layer, a complete reflection effect is formed between the lighting module and the surface cover plate to eliminate the ghosting in the display near the black bezel
Data Source
AI summary
An electronic paper display includes a surface cover plate, a lighting module, a first optical adhesive layer, an electronic paper display module and a second optical adhesive layer. A peripheral area of a bottom surface thereof is provided with a black bezel formed by an opaque or low-light-transmittance material. The bottom surface is disposed with a low-refractive-index transparent resin layer. The lighting module has a light guide plate and multiple point light sources. The point light sources are disposed outside an outer edge of the light guide plate. The lighting module is disposed under the surface cover plate. The first optical adhesive layer glues the surface cover plate and the lighting module. The electronic paper display module is disposed under the lighting module. The second optical adhesive layer glues the lighting module and the light guide plate of the lighting module.