Thermal Printer

Thermal Printer (or direct warm printing) is a propelled printing process which makes a printed picture by particularly warming secured thermochromic paper, or warm paper as it is typically known, when the paper ignores the warm print head. The covering hands dull over the locales where it is warmed, making a photo. Two-shading direct warm printers can print both dull and an additional shading (every now and again red) by applying heat at two particular temperatures.[1] 

Billing printer is an out and out various strategy that uses a glow sensitive ribbon as opposed to warm fragile paper, however uses similar warm print heads.