Project: Spectrum | Keeping It Cool
We want to bring you guys more news on Spectrum OLED development. This time we would like to talk more about cooling. For the monitor to achieve top performance, the monitor should be adequately cooled. This allows the panel to achieve its maximum brightness without increasing the risk of burn-in, a known weakness of OLED panels. Considering just how crucial thermal performance is, we are implementing some updates to the design to accommodate better cooling. Let’s dive in!
First light-up and preliminary findings
In our previous topic, we discussed our first light-up, the first successful attempt at making all our electronics work together. Though this means that we can test a lot of its functionality, the monitor in this form has yet to have its casing or enclosure.
Light-up unit cooling design with the heatsink on top of the scaler.
Testing the image processing and power delivery hardware on this unassembled monitor, all temperatures remained within safe operating temperatures. However, having the electronics out in the open like this makes it much easier for the heat to dissipate into the surrounding air, so it is not a realistic representation of the temperatures these parts may reach once they are enclosed in a metal and flame-retardant ABS plastic housing.
Of course, our engineers are also aware of this. As more test data becomes available, they are making all the necessary adjustments to our mechanical design. This way, we ensure that the monitor is adequately cooled, even though our design is the thinnest among our competitors.
A common way to cool hot components in a small enclosure is to add a fan, which improves airflow. However, smaller fans tend to create a loud, high-pitched noise, and larger fans take up more space. To keep our monitor both slim and silent, we rely on passive cooling. This means that our design needs to consider the natural airflow in and around the monitor.
For this, we have the top part of the box fully perforated. This is for the hot air to go out, which follows the principle that hot air rises. In theory, this movement of air creates a “vacuum” effect which draws cool air in. We have created similar perforation in the bottom of the monitor from which the cool air comes in.
View from the top. Hot air will come out from the perforated finish.
View from the bottom. You can see similar perforations on the inner side of the bottom port indentation. This is where the cool air will come from.
Taking the heat off
We are always actively and smartly thinking about how to get the most out of every component. To better cool the motherboard, we have decided to forego the heatsink on top of the scaler and instead replace it with a thermal interface material (TIM) that will transfer heat directly to the metal shielding that’s already part of the chassis. This metal shielding was initially used to provide more structural rigidity and electronic magnetic interference (EMI) shielding, but in the new design, it will also serve as a heatsink. Since it is as big as the motherboard, it has more surface area than the original heatsink to provide better cooling.
A similar approach also applies to panel cooling. In the Spectrum OLED design topic, we talked about adding the extended frame to support the new placement of the PCB. We have now expanded that frame to be as big as the panel itself, and we will add TIM between this frame and the panel.
So basically, we will have two heatsinks, one for the motherboard and another for the panel! Each is as big as the component it is meant to cool.
Thermal interface material (TIM)
Since we will utilize TIMs as part of the monitor’s cooling, our team explored several options currently available for us to use in our design.
Left: Silicone pad. Right: Graphite sheet
A silicone pad is commonly found on larger electronics such as laptops and tablet computers. It is cost-effective and works very well in most cases. Graphite sheet has a higher thermal conductivity and is commonly found on smaller devices such as phones. The graphite sheet’s higher performance comes with a substantially higher price tag, so we need to base our material decision on what performance is meaningful for our Spectrum OLED.
First sample unit coming!
We have a scheduled sample unit in about two weeks, and all the design changes presented above will be reflected there. So far, our thermal design has been based on the calculations, simulations, and experience of our engineers. Once we have a physical prototype of the monitor, we can add real-world measurements to help refine our design even further.
Of course, we welcome more discussion related to this topic. We would like to know your take on the thermals. Are there things that we are missing? Are there things that we need to look at?
Join in the discussion in our community, and as always, thank you for reading!