LED Illumination System Ceramic Substrate Heat Management
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Solution Overview
Problem
Current illumination systems using LEDs suffer from low efficacy of light emission due to inefficient heat management and light extraction, leading to reduced conversion efficiency of input electric power to emitted optical power, which results in high temperatures and decreased functionality of LED chips.
Innovation Solution
The use of a translucent or transparent polycrystalline ceramic optical substrate as both a heat-spreading means and an optical component, combined with a metallization layer and heat sink, to effectively manage heat and enhance light extraction, allowing for high-power LED operation without temperature constraints and improved light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If LED chips are operated at high power to increase radiant output, then light emission intensity is improved, but temperature rises causing decreased efficacy and functionality
Solution Approach 1:
The patent extracts the light emission function from the heat generation function by using a flip-chip configuration where the LED emits light through the substrate side rather than the bonding pad side. This separation allows heat to be conducted away through the substrate while light is emitted through a different path, resolving the contradiction between high power operation and temperature control
Solution Approach 2:
The patent introduces an intermediary transparent substrate that serves dual functions: as a mounting platform for the LED and as a heat spreading medium. The substrate acts as a mediator between the heat-generating LED chip and the heat sink, enabling effective thermal management while maintaining optical transparency for light emission
2Illumination intensity
If conventional LED mounting is used with bonding pads, then electrical connection is simplified, but emission area is reduced and emission intensity is lowered
Solution Approach 1:
The patent inverts the conventional LED mounting approach by flipping the chip configuration. Instead of mounting the LED with the bonding pad facing up for light emission, the LED is mounted with the bonding pad facing down toward the substrate, allowing light to emit through the substrate side. This inversion eliminates the bonding pad obstruction and maximizes emission area
Solution Approach 2:
The substrate is designed to perform multiple functions simultaneously: providing mechanical support for the LED, serving as an electrical connection pathway, acting as a heat spreader, and functioning as a light emission medium. This multi-functionality compensates for the increased mounting complexity by integrating several functions into a single component
3Use of energy by moving object
If heat is not effectively managed, then LED operation is simplified, but conversion efficiency of electric power to optical power decreases
Solution Approach 1:
The patent merges the heat management functions into the existing substrate structure rather than adding separate cooling components. The substrate is designed to conduct and spread heat from the LED chip across its entire area, utilizing the substrate itself as the heat management mechanism. This integration maintains simplicity while improving conversion efficiency through effective thermal management
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
This solution enables higher radiant power output from LEDs while maintaining high efficiency and reliability, as the ceramic substrate effectively dissipates heat and optimizes light extraction, overcoming the limitations of existing systems by maintaining high performance even at elevated temperatures.
Implementation Method 1
the optical substrate comprises heat-spreading means
Implementation Method 2
a LED substrate provided with a light-emitting layer for emitting light
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
An illumination system has a plurality of light-emitting diode chips (R, G, B). Each light-emitting diode chip comprises a LED substrate (2) provided with a light-emitting layer (1) for emitting light. The LED chips are arranged on an optical substrate (10) with pre¬ determined optical properties. The light-emitting layer of the LEDs faces the optical substrate. Light emitted by the at least one light-emitting diode chip is being emitted via a light-egress window (11) facing away from light-emitting layer. The optical substrate comprises a heat-spreading means. Preferably, the optical substrate comprises a translucent polycrystalline ceramic material acting as heat-spreading means. Preferably, the heat- spreading means comprises a metallization layer (16) and/or a heat sink (17) applied at a side of the optical substrate facing away from the light-egress window. Preferably, the LEDs are embedded in the optical substrate.