LED Light Source Unit for Uniform Medical Illumination

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Solution Overview

Problem

Existing operation theatre lighting devices fail to provide homogeneous, adjustable white lighting with high color rendering index (CRI) and optical efficiency, and suffer from color separation issues when a person obstructs the light.

Innovation Solution

A light source unit comprising a combination of phosphor converted green LEDs, orange-red LEDs, and blue LEDs, arranged in a specific configuration to achieve adjustable correlated color temperature (CCT) between 3580K and 5650K, with a CRI of 90 or higher, and a reduced number of LEDs and reflectors to minimize cost and color separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If traditional halogen or discharge lamps are used with big reflectors, then illumination coverage is achieved, but optical efficiency and color rendering quality are insufficient

Engineering Contradiction:

Improveillumination qualityVSAvoidoptical efficiency

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent segments the single light source into multiple LED sub-light source units, each containing three types of LEDs (phosphor-converted green, orange-red, and blue). This segmentation allows independent optimization of each LED type's spectral characteristics while maintaining overall illumination quality and efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs composite light emission by combining three different LED types with specific spectral characteristics. The phosphor-converted green LED (x=0.35-0.39, y=0.42-0.54), orange-red LED (614-622nm), and blue LED (460-476nm) work together to create a composite spectrum that achieves high CRI (>90) and adjustable CCT (3580K-5650K) while maintaining high optical efficiency.

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If multiple LEDs and reflectors are used to achieve homogeneous lighting, then illumination quality improves, but system cost increases

Engineering Contradiction:

Improvehomogeneity of lightingVSAvoidnumber of LEDs and reflectors

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent merges multiple LED types into integrated LED sub-light source units, where three different LED types are combined in a single modular unit. This merging approach achieves homogeneous lighting through the collaborative emission of different LED types while reducing the overall system complexity compared to using separate reflector systems for each light source type.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Each LED sub-light source unit serves multiple functions simultaneously: it provides the three primary spectral components (green, orange-red, blue), enables adjustable CCT from 3580K to 5650K, achieves CRI >90, and contributes to homogeneous illumination. This multi-functionality reduces the need for separate specialized components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If conventional LED combinations are used, then cost is reduced, but color separation effect occurs when body parts obstruct the light

Engineering Contradiction:

Improvesystem costVSAvoidcolor separation effect

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent carefully selects and optimizes the spectral parameters of each LED type to prevent color separation. The phosphor-converted green LED uses specific CIE coordinates (x=0.35-0.39, y=0.42-0.54), the orange-red LED emits at 614-622nm, and the blue LED emits at 460-476nm. These parameter choices ensure that when body parts obstruct the light, all spectral components are blocked uniformly, preventing the color separation effect while maintaining cost-effectiveness.

Inventive Principle:

Principle #35Parameter changes

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 solution provides high luminous efficiency and uniform lighting with a CRI of 90 or higher, reducing color separation and cost by using fewer LEDs and reflectors, while maintaining adjustable CCT within the specified range.

Implementation Method 1

The phosphor converted green LED employs a blue light emitting chip and a green conversion phosphor in order to generate light with CIE 1931 color location coordinates in the range x = 0,35 to 0,39 and y = 0,42 to 0,54

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

light from the light source unit is incident upon the first reflector after mixed and collimated by the optical device

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

light from the light source unit is incident upon the first reflector after mixed and collimated by the optical device, and incident upon the second reflector after reflected by the first reflector

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentEP2584251B1A light source unit, an illuminating device equipped with the light source unit and medical equipment

Publication Date: 2015.07.15 OSRAM GMBH

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AI summary

The present invention relates to a light source unit (10) comprising at least one LED sub light source unit (20), wherein each LED sub light source unit (20) comprises three types of LEDs: phosphor converted green LED (G), orange-red LED (A) with a wavelength of 614nm-622nm and blue LED (B) with a wavelength of 460nm-476nm, and light generated by the three types of LEDs (A,G,B) is mixed to generate white light.