Sony Ericsson could be about to launch its first PSP mobile phone. A recent patent filing in the US shows the outline of plans for a mobile phone with a rotating display. Underneath, there's an array of keys designed for sophisticated mobile game-playing.

Sony Ericsson's already using popular Sony Walkman and Cyber-shot brands on music and camera-centric handsets. So utilising the Sony PSP brand for a new breed of gaming phone is a natural next step.

The patent application, dated 31 May 2007, features details of a rotating display that changes orientation automatically when switched into landscape mode for gaming. The keys under the display automatically change from numeric keys into gaming controls when the rotary screen is moved.

Speculation about a possible PSP phone from Sony Ericsson has been around for a while. Nokia's N-Gage gaming platform is about to be re-launched as a mass-market proposition for Nokia S60 smartphones. So Sony Ericsson could be going toe-to-toe for the high-end mobile gaming market with a PSP branded device.

No details are yet available as to when a Sony Ericsson PSP mobile phone could be in the shops.