If your goal is to fit as large a keyboard, preferably full QWERTY, into as small a form-factor as possible, while still recognising that people like to use their cellphones in portrait orientation for calls and landscape for messaging, you’ve got yourself a challenge.  It’s a challenge HTC’s latest patent has taken on, though, using a nifty diagonal slider format and simultaneously contradicting our general perception of sliding handsets: that the top section should, when closed, fully cover the bottom.  Unwired View took the patent illustration (shown after the cut) and knocked up this photoshop of how it would work:

At first glance I assumed the keyboard folded somehow, but it’s actually one solid piece: the screen only covers the top two-thirds, with the bottom, numeric keypad portion uncovered for using the handset in portrait mode.  Push the screen to the side and it slides, diagonally, so as to be central above the QWERTY keyboard when held in landscape orientation.

Of course, the buttons needn’t just be numbers and letters: HTC’s patent suggests they could be anything from a ”standard keyboard, a video play key, numeric keys, dialing keys, navigation keys, hot keys, speed dialing keys, a Windows key and an ending key”.  It might be interesting to see gaming controls, too, with the handset operating as a phone in portrait and as a handheld games console when the screen is flicked across.