Project: Spectrum | Designing the Electronics
All shapes and sizes
During the development of Spectrum with OLED, there has been a lot of back-and-forth between the design team, electrical engineers, and mechanical engineers. The electrical engineers try to create parts that fit our specifications and feature requirements, but that also line up with the housing for things such as ports. Meanwhile, the mechanical engineers try to create a housing that can be reliably manufactured, fits our design on the outside, and fits all the required electronics on the inside.
As all of this development takes place at the same time, and changes from one team often require changes from the other, the shape of the motherboard has changed a lot throughout the design phase. These changes were often small, such as a port slightly moving, or a part of the housing becoming a fraction thicker or thinner. A more radical change happened when we decided to move the T-con board that is attached to the display panel from the factory. It greatly changed the size and shape of the space we have available for the remaining electronics.
A selection from the many shapes of the motherboard before we settled on the final design.
When talking about monitors, the display panel gets a lot of attention. And for good reason: it is largely responsible for the user experience. But a lot of the heavy lifting happens behind the scenes, where other components make sure that the panel can do its best work. At the center of everything sits the scaler, the brain of the monitor. Not only is it in charge of image processing, it also interfaces with the user through the controls and the OSD, and it steers many of the monitor’s features. This requires the scaler to be connected to many other chips in the monitor.
But there are many other specialized chips in play. Such as a USB hub chip that lets you connect multiple USB devices through Spectrum, and a USB switch chip that lets the USB hub connect to one of two connected computers, so you can use the KVM switch.
The video signals from the DisplayPort and HDMI ports connect directly to the scaler, but the USB Type-C input can do more than just video. So there is a Power Delivery controller chip that provides the USB-C port with up to 100W on demand, but also a DisplayPort Alt Mode controller chip that splits off the video signal from the USB data signal: one goes to the scaler, the other to the USB hub.
This block diagram of Spectrum ES07D02 gives an idea of how the various chips in the monitor are interconnected.
These components and others make sure your monitor functions as intended. Each takes up physical space, not only on the surface of the motherboard, but also within the housing. As available space changes due to things such as the stand attachment point, the team created height maps to help them fit in all the components. This allows them to place chips like the scaler, which takes up a lot of space as it is cooled by a heatsink, on a part of the board where there is more room.
But the components don’t just exist in a vacuum: they are all interconnected. After all, when you depress the joystick, that signal needs to get to the scaler so it knows to show the OSD. And when you change USB inputs in the scaler-controlled menu, that instruction needs to get to the USB switch controller. And though 100W power delivery has an obvious power requirement, every chip on the board requires some. The are additional circuits just to make sure every component gets exactly the right voltage and current.
Laying out the connections between all of these components is a challenge. Not only must the parts be connected to power and to each other, these connections themselves can sometimes not be allowed to cross or come near one another. A video signal might be carried as a pattern of high-speed, low-voltage bursts of power. Such a delicate signal can easily be disturbed by the electromagnetic field of a nearby trace carrying power.
For each component and connection on the motherboard, the electrical engineering team has to take into account how much physical space is available, but also what it needs to connect to, what other things are near it, and whether there is enough room for it to dissipate any heat it generates.
left: Because of the stand mount, the inside of the housing isn’t flat. | right: The electrical engineers used a height map to indicate how tall components can be on each part of the motherboard.
When we talked about the design of our new monitor, we touched briefly on how the current models have recessed ports on the side. Because the motherboard is placed within a metal housing to block electromagnetic interference (EMI), and the housing is added overtop during assembly, we were not able to get the ports as close to the housing as we wanted.
This time around, we took a completely different approach, by placing the ports on the side of the monitor on their own, separate circuit board. This ‘daughter board’, which connects to the motherboard with a cable, can be attached directly to the housing before the housing is applied, meaning the ports don’t get in the way during assembly. It also allows us to line up the ports exactly how and where we want them, and because it is a small component that only needs to line up with one side of the monitor, we don’t suffer from ‘tolerance stacking’. As a result, the ports on our new monitor sit flush with the housing and no longer require large cut-outs to facilitate bigger plugs, which adds to the clean look of Spectrum with OLED.
left: The current monitors have larger cut-outs and recessed ports. | center: A concept sketch from the electrical engineers. | right: The ports on Spectrum with OLED are flush with the housing and look great.
A lot of thought went into the electronics that drive Spectrum. We’re looking forward to showing you more development news after the Chinese new year celebrations end and the EVT stage kicks into high gear!