Laptops could send video to external displays since their early days. The first ThinkPad-branded laptops introduced in 1992, for example, had ports to mirror VGA signals to bulky CRT monitors. Building on long-established research about the improved productivity of extending a workspace across multiple displays, though, the first external LCD monitors designed for portable use from brands such as AOC and ASUS launched about a decade ago. They could fit into the same bag as a laptop and included a kickstand or folding cover that propped them up. Arriving long before USB-C came on the scene, they used a technology called DisplayLink to receive power and video over a standard USB port.
Nowadays, Amazon lists hundreds of portable monitors that stretch from about 10.5 to 18.5 inches, with 17.3-inch models such as the SideTrak Solo topping out the touchscreen options. (Models smaller than 10 inches are often used for maker projects, security monitoring, or as a display for checking camera output while those above 18.5 inches get significantly thicker and are often used in industrial applications such as digital signage and kiosks). Portable monitors also vary by aspect ratio, touchscreen support, and resolution sizes (FHD, 2.5K and 4K); touch support and higher resolution create the biggest price differences as you step up. Several 15.6-inch FHD devices (a popular choice) can cost less than $100.
Regardless of their many differences, though, these monitors are set up astride the laptop. And even though many of them support power passthrough so that a USB PD cable plugged into the monitor can supply power for the host laptop, that continuity break disrupts the experience. With its Duex and Trio products, Mobile Pixels pioneered attaching a second or even third mobile monitor that could piggyback onto the back of a laptop when closed. But the initial attempts relied on adhesive and magnets and raised concerns about putting stress on the hinge.
To build a better multi-monitor
Now, companies such as Xebec and CrowPi (better known for their Raspberry Pi-based laptops) have added brackets and stands for a better experience. Even so, while having two monitors extend out from the main laptop screen results in a relatively fluid multi-screen experience, the full wingspan can consume a lot of space. You should be on familiar terms with people flying next to you if you try this from a middle seat in coach.
So, much as with urbanization where limited real estate pushes construction from sprawl to tall, monitor makers have begun introducing stacked displays that fold into clamshells much like laptops themselves. Following the introduction of the clamp-mounted LG DualUp, one of the first came from Mobile Pixels. But its Geminos offering consisting of two stacked 24-inch monitors on a stabilizing but ungainly height-adjustable stand was anything but portable, weighing in at 20 pounds,
More modest screen sizes designed for portable use have followed, including dual 14 and 15.6 inch (with optional touch support on the lower display) from early portable monitor vendor Lepow. Introduced in a Kickstarter campaign, it’s already been beaten to market by a few models available on Amazon.com from Virzen, InnoView, and Uperfect, the last of which offers a stacked portable display that has taken the size crown with two 18.5-inch screens.
Bridging the gap
While these displays reintroduce the gap between the laptop’s main display and the external ones, the stacked screens at least offer a minimal gap between their own screens. The approach offers other advantages as well, including a more convenient switch to portrait orientation (albeit one that requires manual screen orientation switching), use of generally larger displays (at 14 inches, the stacked display sizes start around where the side-mounted displays leave off) and better protection for the displays when they are folded.
Finally, while a three-monitor side-mounted setup usually requires using two ports on a laptop (one for each external display), stacked displays use a single connection. On the other hand, you may not like the low angle at which these displays sometimes position the lower screen.
If you like the aesthetic or workflow of a stacked display but don’t need a total of three screens, any number of stands can position a more affordable portable display or tablet above your laptop screen to minimize horizontal footprint. At the other extreme, if you always want the flexibility of a dual-screen option in your laptop, Lenovo’s Yoga Book 9i could be just the choice for you. I’ll delve more into what distinguishes this unique device in a future column.
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Ross Rubin is the founder and principal analyst at Reticle Research. Ross has been an industry analyst focusing on innovation in the technology, media and telecom markets for over 20 years. Prior to founding Reticle Research, he was executive director and principal analyst at The NPD Group, where he provided analysis on a wide range of technology topics and led research spanning devices, access and content. You can follow him on X and Threads @rossrubin.