Reverse Tapered Heatsink for LED Light Obstruction

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Solution Overview

Problem

Conventional LED light bulbs with heatsinks obstruct light output near the base due to the heatsink's design, resulting in reduced light intensity and unpleasant shadows, especially when the bulb is pointed upward.

Innovation Solution

A reverse tapered heatsink design where the width increases from the solid state emitter to the base end, reducing obstruction and enhancing light output by allowing unobstructed emissions over a larger half-angle, typically exceeding 90 degrees.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a conventional heatsink design is used with the widest portion near the solid state emitter, then heat dissipation is effective, but light output near the base is obstructed

Engineering Contradiction:

Improveheat dissipationVSAvoidlight output near base

Core Design Contradiction:

TemperatureVSIllumination intensity

Solution Approach 1:

The heatsink geometry is inverted from the conventional design. Instead of having the widest portion near the solid state emitter, the heatsink has its widest portion at the base end and tapers toward the emitter. This reverse tapered configuration allows light to propagate unobstructed from the emitter through the narrowing section, while the expanded base portion provides effective heat dissipation surface area.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If a heatsink of sufficient size is used to dissipate heat, then thermal management is improved, but light emissions are blocked proximate to the base

Engineering Contradiction:

Improvethermal managementVSAvoidlight emissions near base

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The heatsink design transitions from a uniform cross-section to a tapered three-dimensional structure. The width of the heatsink varies along its length, creating a gradient that allows light to pass through the narrower upper section while the expanded base section provides thermal management. This dimensional variation resolves the conflict between heat dissipation requirements and light emission requirements.

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 reverse tapered heatsink design increases light output below the bulb, reducing shadows and enhancing light distribution without obstructing lateral emissions, thereby providing more uniform illumination.

Implementation Method 1

heat dissipating elements such as heatsinks are commonly provided in thermal communication with high intensity LEDs, since is necessary to prevent a LED from operating at an unduly high junction temperature

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

A reverse tapered heatsink geometry is employed in which a widest portion of the heatsink is disposed between the base end and the solid state emitter

Methodology Applied

Scientific EffectLight propagation: Light

Data Source

PatentEP2446186B1Lighting device with reverse tapered heatsink

Publication Date: 2015.07.22 WOLFSPEED INC

Figure 1~2
Figure 3~5
Figure 6~7B

AI summary

A solid state lighting devices includes a heatsink having a first end arranged proximate to a base end, and a second end arranged between the first end and a solid state emitter, wherein at least a portion of the heatsink is wider at point intermediate the first end and the second end than the width of the heatsink at the second end. Such reverse angled heatsink reduces obstruction of light. A heatsink may include multiple fins and a heatpipe.