Black line sensing, also referred to as a black mark sensor, is a line or mark on a label or tag that is used to identify when to start / stop feeding through a printer. All thermal printers use sensors or optics that read distances between each gap to determine label or tag length. Black marks are one of three methods to determine length. The three are, blackline or black mark sensing, continuous feed and gap sensing.
Paper material with thermal coatings such as tickets or tags used on thermal printers will often require a black line sensor bar to determine start/stop distance. Labels or tags with dark backgrounds can also trick the printer in not “seeing” gap and these will require black lines as well.
If you are unsure how to create the right sensing method for your printer, contact us and show us your product or project. We will make a recommendation that will be guaranteed to work.