If my Brother laser printer starts while I have the ceiling fan going on the same circuit, the breaker will trip. That's the only thing in my house that will do it. It must be a huge momentary current draw.
This happens with my Samsung laser printer too, is it not all laser printers?
It's mostly the fuser that is sucking down all the power. In some models, it will flip on and off very quickly to provide a fast warm up (low thermal mass). You can often observe the impact of this in the lights flickering.