With modern laptop screen dimension ratio ever more approaching the 9:16 rather than 3:4, a second screen that expands upwards rather than sidewise, is increasingly more relevant, as it increases the screen area with minimal increase in the maximum linear dimensions (especially, length of any edge of the screen), making it possible to work in greater diversity of conditions (such as on an an airplane) without bumping into others beside you.
The vertical slide-out dual screen relies on a specialized chassis, which could be based either on small wheels or sliding tracks, that let you slide another screen out upon need. (Not sure though if this is better than simply hinges-based expansion, which could allow for a laptop to be a tablet at the same time. Also, communication link might be a puzzle, with optic link as one of the possilbe solutions.)
[See Picture]. I didn't see that anywhere yet.-- Inyuki, Aug 13 2012 (???) Vertical Slide-Out Dual Screen For Laptops http://universians....deOutDualScreen.jpg [Inyuki, Aug 13 2012] Sideways, but... https://www.mobilepixels.us/products/duexClose enough to baked. [neutrinos_shadow, Jul 07 2020] Vertical too... https://www.digital...op-trends-ces-2020/ [bs0u0155, Jul 09 2020] Mobile Pixels TRIO https://www.mobilepixels.us/Now there are two of them! [neutrinos_shadow, Aug 05 2020] And another... https://yourslide.com/Seems 3 screens is the new black... [neutrinos_shadow, Aug 05 2020] What's wrong with a simple double-fold? The top screen-part folds down toward the keyboard, and ends up glass-to-glass with the middle screen-part. Then that middle part folds toward the keyboard. The parts are so thin these days that the total thickness of the laptop would be quite acceptable.-- Vernon, Aug 14 2012 [Vernon], maybe that you would have to always expand the whole two of the screens to work? (I agree that would be a very minor inconvenience though, and it has its own merits, such as keeping the screens cleaner.)-- Inyuki, Aug 14 2012 Zig-zag fold.
When closed, the" second" screen is the" top", allowing it to be used as a tablet.
Hinge up the main screen and it's a conventional laptop, except the" other side" is a screen too. Could be good for small-scale demonstrations etc. The two displays are treated as separate monitors by the OS.
Fold up the other hinge and now the user is presented with two equal sized displays one above the other, the top one being a touchscreen.
Sensors in the hinges indicate mode changes to the OS, with user overrides from the keyboard.-- 8th of 7, Aug 19 2012 Would also be good for showing off your artwork or taste in wallpapers to the people across the table from you.-- notexactly, May 03 2019 [bs0u0155], that website is a mess. I'm not sure what it was trying to achieve, but it kept jumping around while I was trying to scroll. Also, it must've updated since you looked, because there was nothing about vertical slide-out second screens. (Aside: I came up with the idea of a "2 screen laptop", as shown on that site, in 1990-something; not long after I first heard of touchscreens being an actual thing...)-- neutrinos_shadow, Jul 09 2020 random, halfbakery