1. Readius Polymer Vision
In 2008, before the world we know today, Polymer Vision announced a 5-inch display (which must have seemed giant back then) that closed folds. It had only 16 different shades of gray, with no actual colors. This is the beginning of history.
2. Samsung Continuum
In late 2010 Samsung busted out this phone with a bottom 1.8-inch line display at the bottom of the primary 3.4-inch screen. Similar to the LG V10, it had only one, 4-inch screen, but was divided into three: 3.4-inch main screen, Android keys, and the secondary 1.8-inch screen.
3. Motorola Wilder
In summer of 2011, Motorola released this handset with a 2.8-inch 240 x 320 pixel resolution display, along with a secondary 0.7-inch 96 x 16 pixel display. It had just enough space to see notifications, signal, battery strength, etc.
4. LG Doubleplay
In 2011 LG released their first attempt at a secondary screen. A slider phone with a full QWERTY keyboard, it was split by a secondary 2-inch 480 x 320 pixel display on the bottom.
5. Kyocera Echo
It’s technically not a flip phone, just a double screen - because double or nothing. In 2011, Kyocera announced this dual-screen phone that had two 3.5-inch 480 x 800 pixel resolution, which made one massive 4.7-inch display (which for 2011, was huge).
6. Sony Tablet P
Not to be outdone by it’s Japanese rival, Sony announced something similar in 2012. A tablet that combined two 5.5-inch 1,024 x 480 pixel resolution, it created a much better version of the Echo, with less space in the middle. Still, the idea never kicked off.
7. Medias W N-O5e
Released in 2013 it was pretty similar to other two Japanese handsets. It had two 4.3-inch QHD displays that created one massive 5.6-inch phablet. It could be used either in dual-screen mode or separately.
In 2014 the YotaPhone was announced, and frankly it's the first time anyone took dual-screens seriously. It has an e-Ink display, and the always-on screen can display notifications and other information without using any power.
9. Samsung Galaxy Note Edge
In 2015, Samsung single-handedly brought dual-screens to fame with the release of their newest flagship. Although it’s teeny tiny, it still counts as a secondary screen. A 5.6-inch QHD main display, with a tiny strip, just one inch along the side that displays notifications and other info.
10. LG V10
In late 2015, LG made a splash with this bad boy. It has a main 5.7-inch QHD display, and an additional secondary 1.6-inch screen for notifications and information. Even better, this phone also had two front-facing cameras to produce a wide angle selfie. Two for two, with this handset!
11. Samsung Project Valley
It’s only rumors until now, but by 2016 I expect we will see Samsung with a foldable smartphone. Obviously it will have to sport two QHD screens that fold into one.
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