Prism-Based Optical Lens for Thin Backlight Uniformity

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Solution Overview

Problem

Conventional direct type backlight modules face challenges in achieving lightness, thinness, and uniform illumination due to limitations in light-mixing distance and manufacturing complexity of secondary lenses, particularly with refracting and reflecting type lenses.

Innovation Solution

An optical lens design featuring a recessed surface with prism surfaces of varying orientations and shapes, allowing for adjustable light propagation paths and simplified manufacturing, integrated into a backlight module to enhance illumination uniformity and reduce thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the light-mixing distance of the secondary lens is decreased to achieve lightness and thinness, then the thickness of the backlight module is reduced, but the illumination uniformity deteriorates

Engineering Contradiction:

Improvethickness of backlight moduleVSAvoidillumination uniformity

Core Design Contradiction:

Length of stationary objectVSIllumination intensity

Solution Approach 1:

The secondary lens is divided into multiple lens units, each with a specific light-mixing distance. This segmentation allows the overall thickness to be reduced while maintaining adequate light mixing within each unit, resolving the contradiction between thinness and illumination uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the optical system are assigned different functions: the primary lens focuses light, while the secondary lens units perform light mixing. This local differentiation allows optimization of each component's performance, enabling reduced thickness while preserving illumination uniformity through proper local light-mixing design.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If the number of light-emitting diodes is increased to improve illumination uniformity, then the illumination uniformity is improved, but the device complexity and manufacturing cost increase

Engineering Contradiction:

Improveillumination uniformityVSAvoidnumber of light-emitting diodes

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The light-mixing function is extracted from the light-emitting diodes themselves and assigned to dedicated secondary lens units. This separation allows the LEDs to focus on light emission while the lens units handle light distribution, improving uniformity without increasing LED count.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The secondary lens units serve multiple functions: they redirect light from LEDs, mix light from multiple sources, and distribute light uniformly across the display area. This multi-functionality achieves illumination uniformity without requiring additional light-emitting components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Illumination intensity

If the light-incident surface and light-emitting surface of the reflecting type lens are designed as complicated curved surfaces to increase light-emitting angle, then the light-emitting angle is increased, but the manufacturing precision and cost worsen

Engineering Contradiction:

Improvelight-emitting angleVSAvoidprecision of curved surfaces

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

Instead of using complicated curved surfaces to achieve light redirection, the patent employs prism structures with flat surfaces that utilize total internal reflection. This inverted approach achieves the same light-emitting angle improvement while dramatically simplifying manufacturing requirements.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The complex curved surface geometry is replaced with a prism-based optical system that uses geometric optics principles. This substitution maintains the light-emitting angle performance while enabling precise manufacturing through standardized prism fabrication techniques.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 optical lens design improves illumination uniformity and reduces the number of lenses required, while simplifying manufacturing processes, thereby enhancing the performance and efficiency of backlight modules and display devices.

Implementation Method 1

the propagation paths of the light beam provided by the light source are reflected by the prism surfaces

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

A light-emitting angle of the refracting type lens is only about 75 degrees

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS9829175B2Optical lens, backlight module and display device

Publication Date: 2017.11.28 RADIANT OPTO ELECTRONICS SUZHOU

AI summary

An optical lens, a backlight module and a display device are provided. The optical lens includes a main body, a light-incident surface, a recessed surface and a light-emitting surface. The main body has a top portion and a bottom portion. The light-incident surface is recessed into the bottom portion of the main body. The recessed surface is recessed into the top portion of the main body and is opposite to the light-incident surface, in which the recessed surface has a plurality of prism surfaces, and each of the prism surfaces has a normal line, and directions of the normal lines are different from each other. The light-emitting surface connects the top portion and the bottom portion.