Years ago, I remember printing on a laser printer for the first time in the day took a long time because the fuser had to heat up, but I got a new laser printer recently and it can print in a few seconds first thing in the morning. How is it able to print so fast?
The latest generation of laser printers warm up quickly because they use a new fuser technology, sometimes called "instant warm up". Instead of using a traditional metal roller, which takes a long time to heat, a thin membrane is used in conjunction with a heat lamp and a highly conductive metal heat transfer column. The difference is illustrated below:
On the left, the traditional method is shown. On the right is the new, flexible membrane approach. The thin membrane heats up almost immediately and special column transfers heat directly to the "nip".
A side benefit of the new approach is that the nip is wider, so the quality of the fusing is higher, as well.