Edge-Lit Back Light Module with Concave-Down Luminance for Scanners
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Solution Overview
Problem
Conventional back light modules with uniform luminance distribution often result in lower brightness at the outer portions of scanned images in scanners, affecting scanning quality due to optical and mechanical design limitations.
Innovation Solution
An edge lighting type back light module design featuring a light guide plate with a diffuser and reflecting layer, where the light emitting device, diffuser, or reflector has higher luminous intensity, transmittance, or reflectivity at the outer portions compared to the inner portions, ensuring increased luminance at the outer areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If uniform luminance distribution is provided in the back light module, then the light output appears uniform, but the outer portion brightness becomes lower than the inner portion in scanned images
Solution Approach 1:
The light emitting device is designed with non-uniform luminous intensity distribution, where the outer portions have higher luminous intensity than the inner portion. This local quality variation compensates for the brightness fall-off in the scanned image outer portions, thereby improving scanning quality while maintaining appropriate overall luminance distribution.
2Illumination intensity
If the light emitting device has higher luminous intensity at outer portions, then the outer portion luminance increases, but the overall luminance uniformity decreases
Solution Approach 1:
The light emitting device implements local quality by having different luminous intensity characteristics at different positions along its length. The outer portions emit higher intensity light while the inner portion emits lower intensity light, creating a non-uniform luminance distribution that specifically addresses the brightness fall-off problem in scanner applications.
Solution Approach 2:
The luminous intensity parameter of the light emitting device is varied along its length, with outer portions designed to have higher intensity than the inner portion. This parameter change enables compensation for optical system characteristics that cause brightness fall-off at the edges of scanned images.
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 design enhances the luminance of the outer portions of the back light module, improving scanning quality by increasing light usage efficiency and overcoming the brightness fall-off issues in scanners.
Implementation Method 1
a light guide plate (LGP) for scattering incident light to a light output surface
Implementation Method 2
a diffuser positioned on the light output surface of the light guide plate for diffusing light from the light output surface
Implementation Method 3
a reflecting layer positioned on a reflection surface of the light guide plate for reflecting light into the light guide plate
Data Source
AI summary
Several optical mechanism designs for making luminance of the outer portion of a back light module of edge lighting type to become higher than luminance of the inner portion of the back light module are disclosed in accordance with the present invention. The disclosed optical mechanism designs can cooperate with each other to enhance the optical effect of the back light module. Additionally, the back light modules of the present invention are feasible for use in various scanners or liquid crystal displays.