Backlight Unit Light Splitting Optical Film Uniformity
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Solution Overview
Problem
Backlight units for LCD displays face challenges in achieving a thin profile while providing bright and uniform light to the LCD panel while effectively hiding individual LEDs, as existing diffuser films either fail to provide sufficient uniformity or increase thickness to achieve better results.
Innovation Solution
A backlight unit design incorporating an array of LEDs with a lower stack of light splitting optical films, a color conversion layer, and an upper stack of optical films, including brightness enhancement films, where the optical films feature microstructures such as parallel linear prisms and elliptical lenticular structures to split and distribute light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a diffuser film is placed over the LED array to diffuse light, then light uniformity is improved, but the backlight unit thickness increases
Solution Approach 1:
The patent changes the optical parameters of the film by incorporating light splitting microstructures with specific geometries (prism angles, lenticular curvatures) to achieve superior light diffusion and uniformity while maintaining a thin profile. This transforms the film from a simple diffuser to an advanced optical element that controls light distribution through precise structural parameters.
Solution Approach 2:
The patent creates a composite optical film that combines multiple functions: light splitting microstructures for diffusion, color conversion materials (quantum dots or phosphors) for wavelength transformation, and brightness enhancement features. This multi-functional composite structure achieves both thinness and superior light uniformity that cannot be obtained with conventional single-function diffuser films.
2Illumination intensity
If the diffuser film thickness is increased to improve light uniformity, then light uniformity is improved, but the backlight unit becomes thicker and less suitable for thin displays
Solution Approach 1:
The patent achieves enhanced light uniformity in a thin film by precisely controlling the parameters of light splitting microstructures, including prism apex angles, lenticular focal lengths, and microstructure densities. These parameter optimizations enable the film to diffuse light effectively without requiring increased thickness.
Solution Approach 2:
The patent transitions from relying on thickness (one dimension) to achieve diffusion to using microstructural geometry (adding spatial complexity in other dimensions). The light splitting microstructures create multiple light paths and angular distributions that achieve uniformity through dimensional complexity rather than increased film thickness.
3Object-affected harmful factors
If conventional diffuser films are used to hide individual LEDs, then LED visibility is reduced, but light uniformity and brightness are insufficient
Solution Approach 1:
The patent employs a composite optical film that integrates light splitting microstructures with color conversion materials (quantum dots or phosphors). This composite structure simultaneously diffuses light to hide LEDs and converts wavelengths to enhance brightness and uniformity, achieving both goals that conventional single-function films cannot accomplish.
Solution Approach 2:
The patent optimizes the optical parameters of the film structure, including refractive index matching, microstructure pitch, and color conversion layer thickness, to maximize both LED hiding and light brightness. These parameter adjustments enable the thin film to outperform conventional thicker diffusers in terms of both uniformity and brightness.
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 design achieves a thin profile with improved light uniformity and brightness, effectively hiding LEDs and maintaining high angular spreading, as demonstrated by test results showing increased mean energy and reduced range/mean energy ratios.
Implementation Method 1
a first light splitting optical film that includes a plurality of first parallel linear prisms extending in a first direction on a first side, and a plurality of first elliptical lenticular structures extending in a second direction substantially orthogonal to the first direction on a second side
Data Source
AI summary
A back light unit includes an array of LEDs positioned in rows and columns that emit light from a top surface. A light splitting optical film includes a plurality of inverted pyramids positioned on a first side facing the top surface of the array where each of the plurality of inverted pyramids forms an apex oriented in a direction away from the top surface of the array. A plurality of linear prisms is positioned in a parallel configuration on a second side facing away from the top surface of the array where at least some of the linear prisms form an apex being oriented such that a direction of the apex forms a desired angle with respect to a direction of a row of the array of light emitting diodes.