Panasonic September 4th press conference to reveal 20 inch 4K tablet
The concept tablet will provide for a 4K OLED display at 20 inches. This means that at over 20 inches the resolution would be 3840 x 2160 which provides a pixel density of 220ppi. We first heard about the device back in January and back then we were told that the tablet ran on Windows 8 and used an Intel processor. We will find out shortly if Panasonic changed the configuration to include Android. Considering that Google's open source OS has been used by Panasonic in the past, it is a pretty good possibility, especially if the manufacturer plans on an eventual commercial release of the tablet.
source: Panasonic (translated), GforGames via SlashGear