A bit of googling suggests that Epson's advertising agency goes down the low-cost route of using specialist voiceover artistes, rather than using (expensive) well-known actors. So, unless you work in the industry, you probably won't know the name behing the voice.
All of the names that have come up have been male (which isn't surprising in the IT sector, as male voices seem to be far more commonly used) with just one exception:
http://www.voiceovers-uk.com/voiceover/174/Tamara-Kennedy