Optical Sheet Lens Pattern SAG for Total Reflection Control

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Solution Overview

Problem

Conventional optical sheets cause significant optical loss due to total reflection, leading to reduced brightness and increased production costs, especially when multiple sheets are required to meet modern lighting device specifications, which can compromise the reliability of the resulting device.

Innovation Solution

The optical sheet minimizes total reflection by adjusting the Sag (SAG) of a lens pattern formed on a base member, with lenses of varying sizes and shapes distributed uniformly or randomly, featuring negative curvature and specific angular and spatial arrangements to optimize light transmission and reduce the number of light sources needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If multiple optical sheets are used to meet modern lighting device specifications, then brightness requirements are satisfied, but optical loss increases due to total reflection at each interface

Engineering Contradiction:
ImprovebrightnessVSAvoidoptical loss
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

The patent combines multiple optical functions (light guiding, diffusion, and reflection control) into a single integrated optical sheet with a specific micro-lens array structure. This eliminates the need for multiple separate optical sheets, reducing the number of interfaces where total reflection occurs while maintaining high brightness requirements.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the structural parameters of the optical sheet by introducing a micro-lens array with specific SAG ratios (0.01 to 0.3). This parameter modification optimizes light transmission by controlling refraction and minimizing total reflection at the optical interfaces, thereby reducing optical loss while achieving high brightness.

Inventive Principle:
Principle #35Parameter changes

2Illumination intensity

If multiple optical sheets are required to satisfy recent specifications, then brightness and optical performance improve, but device complexity and production costs increase

Engineering Contradiction:
ImprovebrightnessVSAvoidnumber of optical sheets
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent merges multiple optical sheets into a single integrated component with a micro-lens array structure that performs multiple optical functions simultaneously. This reduces device complexity by eliminating redundant layers while maintaining the brightness performance required by modern specifications.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The optical sheet is designed with multi-functionality, where the micro-lens array simultaneously provides light guiding, diffusion, and reflection control functions that previously required separate optical components. This universal design reduces the overall number of components needed in the lighting device.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Illumination intensity

If multiple optical sheets are stacked to achieve high brightness, then illumination intensity increases, but reliability of the device deteriorates

Engineering Contradiction:
ImprovebrightnessVSAvoiddevice reliability
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent combines multiple optical functions into a single robust optical sheet, eliminating the interfaces between multiple stacked sheets where light loss and potential failure points occur. This single-integration approach improves reliability while maintaining high brightness output.

Inventive Principle:
Principle #5Merging (Combining)

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 approach results in a high-brightness optical device with improved reliability by minimizing total reflection and allowing for a single optical sheet to perform the function of multiple conventional sheets, thereby reducing production costs and enhancing light uniformity and brightness.

Implementation Method 1

Incident light L1 advances toward a lens pattern L2 formed on the surface of an optical sheet. As shown in the figure, total reflection occurs along the optical path and the reflected light comes out to the outside L3, leading to optical loss.

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

conventional optical sheets in current use cause optical loss due to total reflection during the process of receiving incoming light

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2619612B1Optical sheet, optical unit and lighting device using the same
Publication Date: 2019.05.01 LG INNOTEK CO LTD
  • EP2619612B1 patent drawingFigure 1
  • EP2619612B1 patent drawingFigure 2(a)~2(d)
  • EP2619612B1 patent drawingFigure 3

AI summary

The present invention relates to an optical sheet or an optical unit used for a lighting device. In particular, the present invention provides an optical sheet comprising a plurality of lens patterns formed on a base member, where SAG (height H: lens diameter R) of the lens pattern ranges from 0.01 to 0.3. The present invention provides an optical sheet which minimizes total reflection by adjusting SAG of a lens pattern formed on a base member, thereby realizing a high-brightness lighting device.