Backlight Optical Film Orientation for Scratch Visibility Reduction
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Solution Overview
Problem
Conventional liquid crystal display (LCD) devices with dual brightness enhancement films (DBEFs) are prone to scratches during manufacturing, leading to uneven optical performance and visibility of scratches due to differences in brightness distribution across viewing angles.
Innovation Solution
The display device incorporates a backlight module with a light guide, a light source, and optical films where the prisms on the first brightness enhancement film are arranged counterclockwise from 0° to 90°, and the dual brightness enhancement film's transmission axis is oriented counterclockwise from 40° to 50°, reducing brightness increments at larger angles and mimicking the optical performance of unscratched areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the DBEF is used to enhance brightness, then the brightness performance is improved, but the DBEF is readily scratched during manufacturing and scratches become visible
Solution Approach 1:
The patent applies local quality by orienting the transmission axis of the DBEF at a specific angle (45° to 135° relative to the light guide edge) to create directional optical properties. This local orientation control ensures that scratch-induced brightness variations are minimized in the critical viewing directions, making scratches less visible while preserving the brightness enhancement function.
2Illumination intensity
If the transmission axis is perpendicular to prism disposing direction for higher brightness, then brightness is improved, but scratches become more visible due to uneven brightness distribution
Solution Approach 1:
The patent changes the critical parameter of transmission axis orientation from the conventional perpendicular arrangement to a specific angular range (45° to 135° relative to the light guide edge). This parameter modification alters the optical interaction between scratches and light transmission, reducing the contrast between scratched and unscratched areas while maintaining high brightness performance.
3Illumination intensity
If the DBEF is oriented to maximize brightness at certain viewing angles, then brightness is improved, but scratches are more noticeable at larger viewing angles
Solution Approach 1:
The patent introduces asymmetry in the optical system by setting the transmission axis at a specific non-perpendicular angle to the light guide edge. This asymmetric orientation creates a more uniform brightness distribution across different viewing angles, reducing the directional brightness peaks that would otherwise make scratches more visible from certain angles.
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 minimizes the visibility of scratches by approximating the brightness distribution curve of scratched areas to that of unscratched areas, ensuring consistent optical performance and reducing the likelihood of noticing scratches, especially at larger viewing angles.
Implementation Method 1
Prisms 37 are disposed on the BEF 31 which can recycle the light with large incident angles to concentrate the light and enhance brightness
Implementation Method 2
The DBEF 33 having a transmission axis 35 allows the polarization light in the direction of the transmission axis 35 to pass through and recycles the polarization light that is not in the direction of the transmission axis 35
Data Source
AI summary
A display device and a manufacturing method thereof are provided. The display device includes a light guide, a light source, and a brightness enhancement film (BEF), and a dual brightness enhancement film (DBEF). The light guide has a first edge along a first direction and a second edge adjacent to the first edge corresponding to the light source. The BEF is disposed on the light guide and has a plurality of prisms along a second direction which rotates from 0 to 90 degrees with respect to the first direction. The DBEF has a transmission axis along a third direction which also rotates from 0 to 90 degrees with respect to the first direction.