Front Light Module Optical Microstructures for Reflective Display Contrast
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Solution Overview
Problem
Conventional front light modules for reflective displays suffer from decreased contrast due to light being directly scattered upward and not transmitted to the display panel, resulting in invalid light that reduces image clarity.
Innovation Solution
A front light module comprising a light guide plate, an optical film with inclined optical microstructures, and optical clear adhesives, which redirects light beams from the top surface to the bottom surface, minimizing invalid light emission and enhancing light transmission to the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light guide plate with microstructures is used to scatter light, then light can be directed toward the reflective display panel, but some light is scattered upward and becomes invalid light, reducing display contrast
Solution Approach 1:
The optical film is divided into multiple functional layers including a light guiding layer, a first scattering layer with first scattering microstructures, and a second scattering layer with second scattering microstructures. Each layer segments the light path and scattering function to precisely control light direction and minimize upward scattering.
Solution Approach 2:
Different scattering microstructures are designed with different local properties: the first scattering microstructures have specific size and spacing for initial light diffusion, while the second scattering microstructures have different characteristics for final light direction control. This local differentiation optimizes light distribution to reduce invalid light.
2Productivity
If conventional light scattering microstructures are used, then light can be distributed across the display panel, but the contrast ratio decreases due to invalid light
Solution Approach 1:
The optical film performs preliminary light scattering and direction control before the light reaches the display panel. By pre-scattering the light in controlled directions and filtering out upward-scattered light, the system maximizes effective light utilization and improves contrast ratio.
Solution Approach 2:
The patent converts the potentially harmful upward scattering into a beneficial selective transmission mechanism. The second scattering microstructures are specifically designed to block upward-scattered light while allowing downward light to pass through, transforming the harmful scattering effect into a useful light filtering function.
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 solution significantly improves the contrast of reflective displays by increasing the ratio of effective light to invalid light, resulting in a higher contrast ratio of approximately 1.86:1, compared to 0.87:1 without the optical film and microstructures.
Implementation Method 1
the optical microstructures with the light receiving surface and the backlight surface are used to reflect the light beam emitted from the top surface of the light guide plate to the bottom surface
Implementation Method 2
a light guide plate is provided, and the light source emits light beams toward the side of the light guide plate. After the light beam enters the light guide plate
Data Source
AI summary
A front light module including a light guide plate, a light source, an optical film, and a first optical clear adhesive is provided. The light guide plate has a top surface, a bottom surface opposite to the top surface, and a light input surface connecting the top surface with the bottom surface. The light source is disposed beside the light input surface. An optical surface of the optical film facing away from the light guide plate has a plurality of optical microstructures. Each of the optical microstructures is a recess, and has a light receiving surface more adjacent to the light input surface and a light back surface further away from the light input surface. The optical clear adhesive is disposed between the light guide plate and the optical film in a fully bonding manner. An electrophoretic display is also provided.