Compact Lens Array for Uniform LED Color Mixing

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Solution Overview

Problem

Conventional LED illuminating devices with changeable correlated color temperature face challenges in miniaturization due to large lens diameters and thickness, leading to non-uniform light emission and potential perception of broken LEDs when some light sources are turned off, along with chromatic aberration issues.

Innovation Solution

A compact lens design featuring a first surface with light incident surfaces, including three-dimensional and partial cylindrical surfaces, and a total reflection surface, allowing light from different sources to mix uniformly, reducing volume and preventing dark areas when sources are turned off, while improving light extraction efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a lens is configured to cover all LEDs as a whole to achieve uniform light mixing, then light mixing uniformity is improved, but lens diameter and thickness become very large

Engineering Contradiction:
Improvelight mixing uniformityVSAvoidlens volume
Core Design Contradiction:
Stability of the object's compositionVSVolume of stationary object

Solution Approach 1:

The lens is divided into multiple lens units, each corresponding to one or more LEDs. Each lens unit has its own light incident surface and light emergent surface. This segmentation allows each lens unit to be compact while collectively achieving uniform light mixing when all LEDs are activated.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If separate lenses are assigned to different groups of LEDs with different correlated color temperatures, then correlated color temperature adjustment is improved, but dark areas appear when some LEDs are turned off

Engineering Contradiction:
Improvecorrelated color temperature adjustmentVSAvoidperception of broken LEDs
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

Each lens unit is designed with a universal light incident surface that can receive light from its assigned LED(s) and also from other LEDs. This multi-functionality ensures that when some LEDs are turned off, their light paths are still covered by other lens units, preventing dark areas and maintaining the appearance of uniform illumination.

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

3Adaptability or versatility

If separate lenses are assigned to different LEDs, then individual LED control is improved, but chromatic aberration occurs between different lens regions

Engineering Contradiction:
Improveindividual LED controlVSAvoidlight emission uniformity
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

Each lens unit has optimized local optical properties with specific refractive indices and surface curvatures tailored to its assigned LED(s). This local optimization ensures that each lens unit properly focuses and directs light from its specific LED(s), while the overall arrangement maintains chromatic consistency across the entire lens assembly.

Inventive Principle:
Principle #3Local quality

4Area of stationary object

If lens diameter is increased to cover all LEDs, then light coverage is improved, but device miniaturization is hindered

Engineering Contradiction:
Improvelight coverage areaVSAvoiddevice volume
Core Design Contradiction:
Area of stationary objectVSVolume of stationary object

Solution Approach 1:

The lens array transitions from a single large planar lens to multiple smaller lens units arranged in a three-dimensional configuration. This dimensional transformation allows the system to cover the same LED array area while reducing the overall profile height and enabling better spatial utilization, thus facilitating device miniaturization.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 compact lens array achieves uniform light mixing and emission, enhancing light extraction efficiency and preventing the perception of broken LEDs, while allowing for independent control of luminance and changeable correlated color temperature.

Implementation Method 1

the light incident surfaces comprise a plurality of three-dimensional surfaces assigned to different light sources, a part of light from one light source can enter the lens from one three-dimensional surface assigned to the one light source, and the other part can enter the lens from one three-dimensional surface that is not assigned to the one light source

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

the first surface comprises: light incident surfaces, from which light enters the lens; and a total reflection surface, on which a part of light entering the lens is totally reflected

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2875395B1Lens, lens array and illuminating device
Publication Date: 2017.12.06 OSRAM GMBH
  • EP2875395B1 patent drawingFigure 1
  • EP2875395B1 patent drawingFigure 2A~2B
  • EP2875395B1 patent drawingFigure 3A~3B

AI summary

The present invention relates to a lens, a lens array and an illuminating device. The lens comprises a first surface and a second surface, wherein the first surface comprises: light incident surfaces, from which light enters the lens; and a total reflection surface, on which a part of light entering the lens is totally reflected, the second surface comprises a light emergent surface, wherein the light incident surfaces comprise a plurality of three-dimensional surfaces assigned to different light sources, a part of light from one light source enters the lens from one three-dimensional surface assigned to the one light source, and the other part enters the lens from one three-dimensional surface that is not assigned to the one light source. The lens has a compact structure and can uniformly mix colors.