Summary of Solid State Lighting Technology Benefits
Many of the general advantages of our magnetic connector technology is demonstrated on the General Technology page. Solid state lighting applications also benefit from the simplicity of design, ease of attachment, mechanical robustness, planar contact geometry and stable contact forces of those generic applications. When it comes to solid state lighting, as opposed to just using LEDs to show contact continuity, there are some additional benefits that come with the technology available that will be highlighted below. Offerings include both magnetic systems and non-magnetic technology relevant to SSL applications.
Since thermal management is a critical issue for LED reliability, this area will be discussed first. The lack of pins and plugs make our technology capable for environmental sealing for both lighting modules and fixtures. Please check out the wet test video below.
Thermal management for LED lighting
The operating life of LEDs is dependent upon extracting thermal heat from the LED substrate. One way to do this is to incorporate an integral heat sink into a LED puck to transfer this heat from the LED to the ambient environment. The alternative is to have an external heat sink and a thermal bridge to the LED substrate. Whether you choose one or the other, our patented and patent -pending technology has the capability to provide an easy design path to satisfy a wide range of performance and aesthetic objectives. While the discussion below focuses on low-voltage LED lighting, there are possibilities to apply elements of the technology shown to other types of removable modules such as cameras, antennae, chemical sensors, charging modules, etc.
Pucks with Integral Heat Sinks
In some applications, it makes more sense to have magnetic modules with self-contained thermal management tailored to the specific LED used with less dependence upon the fixture to which the pucks will be mounted. Below are examples of magnetic LED pucks that contain integral heat sinks. An advantage of an integral heat sink is that thermal management is somewhat independent of how electrical connections are made. A key feature of our magnetic connection technology is that one LED puck is compatible with so many different electrical and mechanical mounting configurations as shown below. This makes it not only possible to reposition an LED puck along a track or set of cables, you can move the same puck between a track light, a cable light, a dedicated socket, a grid or a hidden contact panel.Our magnetic connector technology makes a robust electrical and mechanical attachment system to rigid and flexible cables and tracks for both indoor and outdoor use. The rigid cable implementations are essentially just larger variants of the formed wire desk lamps that were used to demonstrate mechanical tolerance robustness on the General Technology page. Patented spacer technology makes system installation and customization easy for both straight and curved runs.
The surface area of the heat sink can simply be scaled to the maximum temperature rise design point for a particular application environment and lifetime expectation for a particular LED. The pucks shown use Cree CXA 1304 LEDs driven at 400 mA with 9.6 VAC and have a magnetic attachment force exceeding their weight by more than an order of magnitude on flat electrodes. The heat sinks above which provide LED case temperature rise of less than 30 degrees C over ambient may be larger than needed for your particular application. The basic magnetic LED puck system above is not limited to rigid cables for electrodes. The very same pucks work equally well with flexible cable systems, rigid rod systems, flexible flat tracks and rigid flat track systems. In all cases,the relative insensitivity to mechanical variation of the patented magnetic connector technology compensates for slightly non-parallel electrode geometries.
These integral heat-sink pucks are compatible with more planar electrode assemblies. For example, here's a panel with parallel rod electrodes embedded in the surface. Pucks can be mounted anywhere along the length of the panel between any two adjacent rods.
If you want to visually conceal the electrodes, this can also be done. The panel below has the electrodes hidden under a glossy green layer. A matte finish or a covering with graphics would be less noticeable. Even if you want to make the location of the electrodes truly invisible, that's no problem. To have an electronic puck that can be attached anywhere in any rotational orientation on a surface simply requires a three-contact puck and a series of electrodes with prescribed geometries. This much less constraining than inductive energy transfer systems.
Water resistant electrode track lights
As mentioned above, connections built into the case of a product can be environmentally sealed. On the General Technology page, there was a demonstration of an array of exposed contacts that only had voltage present when a module was attached. That's one form of inadvertent finger contact or short-circuit prevention, but it has some limitations on requiring specific contact positions. When it comes to SSL demonstrations of our technology, it is also possible not only to have short-circuit protection for the fixture in isolation, but also to have water resistance when there is electrical current flowing through a mated connector pair. And this doesn’t require any unsightly gasket that detracts from the clean lines of your product.
Below is a video of the LED puck above being supplied power from a hidden track system immersed in a tank of water in homage to the classic John Cameron Swayze commercials for Timex. Just like those old Timex commercials, this just a quick, dramatic demonstration of water resistance to show capability for outdoor track light use and to pique your interest. We didn't measure temperature rise over ambient, but the integral heat sink is certainly larger than needed for this water-cooled environment.
The pucks in the panel videos above are essentially the same other than some additional features for environmental sealing. The heat sink fins and housings can be made in virtually any shape, form or color to tailor thermal properties, LED type, electrical, optical and industrial design objectives without affecting the basic mechanical design of the fixture. Similarly, a wide-range of compatible mounting fixture types were illustrated to show system capabilities. Next, some of the system design trade-offs possible by sharing the LED thermal management with the fixture will be considered.
Pucks for Heat Sinking to Mounting Fixtures
A smaller lighting puck is possible when the track system provides heat sinking for the LED. Below is an example of a magnetic LED puck with a thermal bridge to an external heat sink. Some of the magnetic attractive force is used to provide efficient thermal contact for the thermal bridge. Early in our development effort, an 8 mm thick, 50 mm diameter prototype puck using Apex patented technology was quickly built and tested using the identical Bridgelux 800 lumen LED, power supply and heat sink found in a commercially-available socketed twist-on module. (Test details available under NDA.) Even without using any thermal interface material between the LED substrate and the heat sink, the measured LED substrate temperature rise was less than 2°C/W operating at the normal 12 watts operating power. Although using a thermal pad or grease is recommended to bridge mechanical discontinuities and improve thermal transfer to the heat sink, this worst case scenario result shows the capability of the patented technology to handle mechanical misalignment of the LED substrate to an external heat sink effectively. This thermal contact self-adjustment capability is independent of the electrical contact self-adjustment capability described elsewhere.
Below is a video showing an improved version of a magnetic puck for attachment to a flush mount track. The overall size of the track assembly will depend upon its shape, the number of modules to be mounted on the track, their heat sinking requirements and the installation environment.
And these thermal interface pucks can be made quite small. Shown below is a prototype demonstration puck using a Cree XP-C LED. Compared to the penny, the module has a smaller diameter, less than four times as thick, but less than half the penny's weight. Even in this small package, the pressure on the thermal interface is 650 grams/square centimeter for efficient heat transfer. Even with this impressive thermal interface bias force, the force on each of the electrical contacts making the electrical connection and holding the module to the rail electrodes is over 100 times the weight of the module.
Axial rail electrode systems
Conventional cable lighting systems typically have turnbuckles and heavy duty mounting fixtures, in part to handle the weight of the fixtures. The fixture weight is increased as the ability to tilt and rotate the fixtures adds mass to the fixture. The magnetic fixtures above with integral heat sinks weigh in at only 56 grams, which lessens the requirements on electrode mounting systems. However, the only light directional capability built into the puck itself are replaceable or rotatable lenses. We also have patented and patent pending technology providing additional degrees of freedom that can be used with both magnetic and non-magnetic contact systems. Axial rail systems provide the same ability to move a fixture along the length of a track rail as the examples above, but in addition allow the fixture to rotate around the axis of the rail. Demonstrations of these systems are currently in development.
Wondering if this technology can do ...?
The main purpose of the examples above is to demonstrate some of the capabilities of our patented, patent-pending and trade secret technologies. If you need more information on what is demonstrated above, in particular, whether it is possible to achieve a specific capability with your product, please contact us to start a dialogue.