Besides piano, there were other keyboards used for Queen concerts. It all began when Queen released Flash's Theme as a single in late 1980. They introduced the song to the set (they 'had to', as it was a massive hit in Europe, where they were touring) on 6th December and it s very first rendition had no keyboards as Brian played it all on guitar. From the next concert onwards, however, he was moved to keyboards for the first half of the song: he played piano and then switched to synth for the main hook of the song (the one that follows each vocal phrase in the verse).
Electric and electronic keyboards required external amplification but no specific details have been disclosed so far. Most likely, they were connected to the mixing console and then fed to the P/A. The main electric or electronic keyboards used by either the band or their accompanyists on tour were:
Oberheim OB-X synthesiser (late 1980 to early 1981).
Roland Jupiter 8 synthesiser (late 1981 to 1992).
Oberheim OB-Xa synthesiser (1982 - 1985).
Roland VP-330 vocoder (1984 - 1986).
Yamaha CP-80 electric grand piano (1984-1985).
Yamaha DX-7 synthesiser (1986 - 1992).
E-MU Emulator II+ (1986).
From 2005 onwards (perhaps even before that) Spike's been endorsing Korg products, using, among others, a CX-3 organ, two Triton Extreme LE's (2005 - 2006), M3 88 (2008) and a microKorg (2005-2006).