LED Lighting Device Thermal Contact via Exit Window
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Solution Overview
Problem
Current LED-based MR 16 lamps with glass encasements suffer from poor thermal conductivity, limiting heat dissipation and impacting the performance of LEDs, as glass has a thermal conductivity of about 1 W/(m·K, which is inferior to metal casings like aluminum.
Innovation Solution
A lighting device design featuring a recessed exit window for direct thermal contact with the light source substrate, a funnel-shaped body with a thermal filler, and a biasing element to enhance heat transfer, along with thermal glue for improved thermal conductivity and light focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If glass encasement is used for LED lamps, then low cost and sustainability are achieved, but thermal conductivity deteriorates leading to poor heat dissipation
Solution Approach 1:
A thermal conductor element is introduced as an intermediary between the light source substrate and the exit window. This mediator has high thermal conductivity and facilitates heat transfer from the LED substrate through the glass exit window, resolving the contradiction between using inexpensive glass encasement and achieving effective heat dissipation.
2Temperature
If active cooling techniques are used, then thermal performance is improved, but device complexity and cost increase
Solution Approach 1:
The lighting device utilizes its own structural elements (exit window, thermal conductor element, and optionally the funnel-shaped body) to perform the cooling function. The system is designed to conduct heat away from the LED substrate through thermally conductive paths already present in the optical and structural components, eliminating the need for separate active cooling systems like fans or heat sinks.
3Temperature
If thermal contact between light source substrate and exit window is established, then heat transfer is improved, but manufacturing precision requirements increase
Solution Approach 1:
The thermal conductor element changes the thermal parameters of the contact interface. By introducing a material with high thermal conductivity between the substrate and exit window, the system achieves effective heat transfer even with moderate manufacturing tolerances, as the thermal conductor compensates for imperfect thermal contact.
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 significantly improves heat transfer by facilitating direct contact between the light source and exit window, reducing the light source temperature by about 50% and enhancing light emission directionality.
Implementation Method 1
the light source substrate is held in physical contact with the exit window, thereby enabling thermal contact between the light source substrate and the exit window
Implementation Method 2
a thermal filler is arranged between the inner and outer part. The thermal filler will improve the thermal conductivity of said inner and an outer part and thus the heat transfer from the light source towards and through the funnel-shaped body to the environment
Data Source
AI summary
The disclosed embodiments relate to a lighting device (1) comprising an exit window (2) and a light source substrate (3) arranged to carry at least one solid-state light source (4), the at least one light source (4) being arranged to emit light through the exit window (2). The exit window (2) is shaped to allow a front surface of the light source substrate (3) to be brought into physical contact with a surface of the exit window facing the light source substrate (3), and in that the light source substrate (3) is held in physical contact with the exit window (2), thereby enabling thermal contact between the light source substrate (3) and the exit window (2). Since thermal contact between the exit window and the light source substrate is secured, the heat transfer of the lighting device will be improved.