Is there any halachical problem with laser printing of divre tora/sheimos?
Because the image of the to-be-printed page appears on the drum, and
- transferring the toner on the paper hence "erases" the image from the drum, or
- subsequent printings could erase previous image residue, especially when the printing process was interrupted.
As suggested, here is a rough description of the process.
- An electrostatically-coated cylinder (the "drum") is charged with electricity.
- A laser light ranges over the drum surface, while its intensity modulated opposite to ink intensity on the image (low intensity at the letters' place). In other words, the document is projected onto the drum via laser light.
- The more light hits a point, the more the electrostatic charge drops here.
- Toner powder is thrown on the drum, more attaching where the charge is still high.
- At this instant, we can see the document "drawn" in powder onto the drum.
- Paper sheet is connected to an electric potential, while inserted under the drum, thus attracting the powder.
- Paper passes under a heater, the fuser, that fixes the powder on the paper (toner is powder of plastic).