By Euan Rocha TORONTO (Reuters) – BlackBerry Ltd plans to introduce high-end smartphones that cater to keyboard aficionados in the coming 18 months, in an effort to win back core corporate and government clients who have shunned the companys touch-screen devices. Chief Executive John Chen said in an interview that the companys engineers have designed at least three different next-generation handsets that are being kicked around right now. The focus is going to be very keyboard centric, said Chen, the former Sybase CEO who took the reins of the Canadian company just over four months ago. Chen, viewed by tech industry insiders as a turnaround artist, wants BlackBerry to zero in on its core base of corporate and government clients, and on its services arm, which secures mobile devices on the internal networks of big clients. BlackBerry reported a fiscal fourth-quarter loss on Friday.