A viewscreen is a screen or display that allows you to see something, like a movie, TV show, or a computer program. It is called a viewscreen because it gives you a view of something that is happening or being shown on the screen. Full definition
Next he has Nancy and Jen scan the passengers from a set of viewscreens in the galley and let him know if anyone is using a phone — or even looks like they might be using one. (eclipsemagazine.com)
Useful aerial photography, dark location shooting to sell the power outage, and a helpful thermographic viewscreen ready to reveal surprises comprise the smooth work from cinematographer and short film specialist Mark Farney. (chicagoindiecritics.org)
While the iPhone may arguably be the more convenient device to snap a photograph with, the iPad offers a gigantic 9.7 - inch viewscreen to properly frame and snap your photographs and video. (imore.com)