LCD Backlight Brightness via Reflective Optical Sheet
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Solution Overview
Problem
The use of LEDs as light sources in liquid crystal display devices results in light absorption by the Flexible Printed Circuit (FPC) when overlaid on the light guide panel, leading to reduced brightness due to the mixing of FPC colors with the screen, necessitating a solution to minimize the frame width of the back light.
Innovation Solution
An optical sheet with a colored reflective area is placed between the light guide panel and the circuit board, guiding absorbed light back to the light guide panel, thereby enhancing the brightness by reducing light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the FPC is overlaid on the light guide panel to reduce frame width, then the frame width is reduced, but light is absorbed by the FPC resulting in lowered brightness
Solution Approach 1:
The patent applies the principle of converting harm into benefit by using the FPC's light absorption characteristic in a beneficial way. Instead of treating the FPC's light absorption as a harmful effect to be eliminated, the invention uses a light-reflective member to redirect absorbed light back toward the light guide panel, thereby converting the harmful absorption into a useful light redirection mechanism that maintains both compact frame width and adequate brightness.
Solution Approach 2:
The patent introduces a light-reflective member as an intermediary element between the FPC and the light guide panel. This intermediary redirects the light that would otherwise be absorbed by the FPC, serving as a mediator that preserves the FPC's necessary electrical function while mitigating its harmful optical effect, thus enabling both small frame width and high brightness to coexist.
2Length of stationary object
If the FPC is overlaid on the light guide panel to reduce frame width, then the frame width is reduced, but the FPC color mixes with screen colors
Solution Approach 1:
The patent converts the harmful color mixing effect of the FPC into a beneficial outcome by using the light-reflective member to redirect light away from the FPC's colored area. This prevents the FPC's color from mixing with the screen colors while still allowing the FPC to be positioned for electrical connection, thus maintaining both compact design and color purity.
Solution Approach 2:
The patent effectively extracts the harmful optical function from the FPC by introducing the light-reflective member that separates the electrical function (performed by the FPC) from the optical function (performed by the light-reflective member and light guide panel). This extraction allows the FPC to be positioned for electrical connection without its color interfering with the display.
3Object-affected harmful factors
If a light blocking material is provided on the FPC to prevent color mixing, then color mixing is prevented, but light absorption increases resulting in lowered brightness
Solution Approach 1:
Instead of blocking light with a light-blocking material on the FPC, the patent inverts the approach by using a light-reflective member to actively redirect light away from the FPC. This inversion achieves the same goal of preventing color mixing while avoiding the harmful side effect of increased light absorption, as the light is reflected rather than blocked.
Solution Approach 2:
The patent uses a light-reflective member as an intermediary that performs the function of preventing color mixing without the drawbacks of light-blocking materials. This intermediary redirects light around the FPC, achieving color separation while maintaining light transmission 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
This configuration effectively redirects absorbed light, increasing the overall brightness of the back light and maintaining a smaller frame width, thus addressing the issue of reduced brightness caused by FPC absorption.
Implementation Method 1
a colored area formed with a reflective member is provided in a portion of the optical sheet, and the colored area is provided between the light guide panel and the circuit board
Data Source
AI summary
The present invention provides a liquid crystal display device having a back light for irradiating a liquid crystal panel with light. An LED as a light emitting element is provided on a light guide panel provided in the back light, and a reflection member is provided on an optical sheet in the vicinity of an inclined plane of the light guide panel to reflect the light going out of the inclined plane toward the light guide panel. Furthermore, a convex portion of the light guide panel is formed between a plurality of light emitting elements, and an adhesive member is also provided between the convex portion and the optical sheet to ensure tight adhesion between the light guide panel and the optical sheet.