Monolithic LED Array Package with Series Circuit and Lens

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Solution Overview

Problem

Conventional LED packages face challenges in achieving high light output efficiency and compactness, particularly in delivering light flux levels above 1000 lumens from a small optical source, due to heat retention issues, optical losses, and the need for large secondary optical elements, which increases costs and reduces efficiency.

Innovation Solution

A monolithic LED package design featuring a single or multiple color LED chip array on a planar substrate with an overmolded lens, where LED chips are connected in series or series/parallel configurations to optimize current density and voltage for efficient light emission, reducing the number of external contacts and enhancing thermal dissipation, allowing for compact and efficient light output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional LED packages use reflective cups or metal reflectors to direct light, then light direction control is improved, but optical losses increase due to less than 100% reflectivity

Engineering Contradiction:
Improvelight direction controlVSAvoidoptical losses
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

The patent removes the reflective cup/reflector component entirely from the LED package structure. Instead of using reflection to direct light, the invention employs a lens directly coupled to the LED chip to refract and direct light output, thereby eliminating optical losses associated with reflective surfaces while maintaining effective light direction control.

Inventive Principle:
Principle #2Taking out (Extraction)

2Productivity

If single LED chips are operated at high current to achieve high light output, then luminous flux is improved, but heat retention increases reducing lifetime

Engineering Contradiction:
Improveluminous fluxVSAvoidheat retention
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The patent divides the LED light source into an array of multiple individual LED chips rather than using a single high-current chip. Each chip operates at lower, safer current levels, distributing the heat generation across multiple components. This segmentation allows achieving high total luminous flux while maintaining lower operating temperatures and extending package lifetime.

Inventive Principle:
Principle #1Segmentation

3Productivity

If multiple LED packages are mounted on a circuit board to achieve high luminous flux, then light output is improved, but device size and complexity increase

Engineering Contradiction:
Improveluminous fluxVSAvoidassembly complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent combines multiple LED chips into a single integrated package structure with a common lens and substrate, rather than mounting separate LED packages on a circuit board. This merging approach achieves high luminous flux from what appears to be a single component, reducing assembly complexity and enabling more compact designs while maintaining high light output.

Inventive Principle:
Principle #5Merging (Combining)

4Illumination intensity

If conventional LED packages use large secondary optical elements to shape light output, then beam control is improved, but cost and device size increase

Engineering Contradiction:
Improvebeam controlVSAvoidcost
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent integrates the optical shaping function directly into the lens that is already part of the LED package structure. This single lens performs multiple functions: focusing light from the LED chip, directing light output, and shaping the beam pattern. By making the lens multi-functional, the invention eliminates the need for separate secondary optical elements, reducing cost and device complexity while maintaining effective beam control.

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

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 design achieves high luminous flux greater than 800 lumens at color temperatures below 3000K with improved efficiency, reduced component size, and lower driver costs by optimizing LED chip size, voltage, and current density, while minimizing 'dead space' and optical losses.

Implementation Method 1

Light emitting diodes (LED or LEDs) are solid state devices that convert electric energy to light

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

The reflective cup may be filled with an encapsulant material 16 which may contain a wavelength conversion material such as a phosphor. Light emitted by the LED at a first wavelength may be absorbed by the phosphor, which may responsively emit light at a second wavelength

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentEP2304817B1White light emitting package comprising LED array
Publication Date: 2020.01.08 WOLFSPEED INC
  • EP2304817B1 patent drawingFigure 1a~2
  • EP2304817B1 patent drawingFigure 3~4c
  • EP2304817B1 patent drawingFigure 4d~6b

AI summary

An LED component comprising an array of LED chips (62) mounted on a planar surface of a submount (64) with the LED chips capable of emitting light in response to an electrical signal. The LED chips comprise respective groups emitting at different colors of light, with each of the groups interconnected in a series circuit. A lens (66) is included over the LED chips. Other embodiments can comprise thermal spreading structures included integral to the submount and arranged to dissipate heat from the LED chips.