Front Light Module Halation Suppression via Inverted Ink Layer
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Solution Overview
Problem
Conventional front light modules for reflective display devices, such as electrophoretic display devices, suffer from halation issues due to the placement of ink layers on the lower surface of the protective cover plate, causing light to be reflected away from the display region and resulting in unwanted glare, especially with non-black inks.
Innovation Solution
A front light module design featuring a protective cover plate with an appearance color layer on its upper surface, covered by a functional layer, which reduces halation by minimizing the distance light travels before reflection, thereby keeping the reflection point closer to the ink layer and reducing glare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the ink layer is coated on the lower surface of the protective cover plate, then the aesthetic appearance is achieved, but halation occurs around the display region due to light reflection
Solution Approach 1:
The ink layer is inverted from the conventional lower surface position to the upper surface of the protective cover plate. This inversion changes the light interaction mechanism: instead of light reflecting off the ink layer after traveling through the cover plate thickness (causing halation), the ink layer is now positioned where it can be covered by a functional layer, eliminating the halation problem while maintaining aesthetic appearance.
Solution Approach 2:
A functional layer is introduced as an intermediary between the ink layer and the external environment. This functional layer covers the ink layer on the upper surface, preventing light from reflecting off the ink layer and causing halation, while still allowing the aesthetic appearance to be maintained.
2Strength
If the protective cover plate has certain thickness, then structural strength is provided, but light travels a longer distance and reflects away from the display region causing halation
Solution Approach 1:
The ink layer position is inverted to the upper surface and covered by the functional layer, which eliminates the halation issue caused by light traveling through the thick cover plate and reflecting off the ink layer. The cover plate thickness is maintained for structural strength, but the halation problem is solved by the inverted configuration.
Solution Approach 2:
The functional layer covering the ink layer converts the potential harmful reflection into a beneficial configuration where the light path is controlled. The functional layer prevents the harmful reflection that would occur with a thick cover plate, turning the thick plate's structural advantage into a benefit without the halation drawback.
3Shape
If non-black ink is applied for aesthetic purposes, then color appearance is enhanced, but halation becomes more problematic due to increased light reflection
Solution Approach 1:
Non-black ink layers (such as colored or patterned inks) are inverted to the upper surface and covered by the functional layer. This allows the color appearance to be enhanced for aesthetic purposes while the functional layer prevents the halation that would otherwise occur with these reflective non-black inks.
Solution Approach 2:
The functional layer serves as an intermediary that allows non-black ink to be applied for aesthetic enhancement while preventing the harmful halation effect. The functional layer mediates between the aesthetic requirement for colored ink and the need to eliminate light reflection issues.
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
Effectively suppresses halation by ensuring that the reflection point of oblique light is closer to the ink layer, minimizing the visibility of glare compared to conventional designs where the ink layer is on the lower surface, thus enhancing the display's clarity and usability in low-light environments.
Implementation Method 1
The light guide plate may guide illumination light emitted by the light source to the reflective display panel
Implementation Method 2
The reflective display panel reflects the illumination light to generate image light
Data Source
AI summary
A front light module including a light guide plate, a light source, a protective cover plate, an appearance color layer, and a functional layer is provided. The light guide plate has a first surface, a second surface opposite to the first surface, and a light incident surface connecting the first surface to the second surface. The light source is disposed beside the light incident surface and configured to emit light toward the light incident surface. The protective cover plate is disposed on the first surface, and the protective cover plate has a third surface facing away from the light guide plate and a fourth surface facing the light guide plate. The appearance color layer is disposed on a portion of the third surface. The functional layer covers the appearance color layer and the third surface. An electrophoretic display device is also provided.