What are Ink Jets, and How They Work

Non-impact – These printers do not touch the paper when creating an image. Inkjet printers are part of this group, which includes:

  • Inkjet printers, which are described in this article, use a series of nozzles to spray drops of ink directly on the paper.
  • Laser printers, covered in-depth in How Laser Printers Work, use dry ink (toner), static electricity, and heat to place and bond the ink onto the paper.
  • Solid ink printers contain sticks of wax-like ink that are melted and applied to the paper. The ink then hardens in place.
  • Dye-sublimation printers have a long roll of transparent film that resembles sheets of red-, blue-, yellow- and gray-colored cellophane stuck together end to end. Embedded in this film are solid dyes corresponding to the four basic colors used in printing: cyan, magenta, yellow and black (CMYK). The print head uses a heating element that varies in temperature, depending on the amount of a particular color that needs to be applied. The dyes vaporize and permeate the glossy surface of the paper before they return to solid form. The printer does a complete pass over the paper for each of the basic colors, gradually building the image.
  • Thermal wax printers are something of a hybrid of dye-sublimation and solid ink technologies. They use a ribbon with alternating CMYK color bands. The ribbon passes in front of a print head that has a series of tiny heated pins. The pins cause the wax to melt and adhere to the paper, where it hardens in place.
  • Thermal autochrome printers have the color in the paper instead of in the printer. There are three layers (cyan, magenta and yellow) in the paper, and each layer is activated by the application of a specific amount of heat. The print head has a heating element that can vary in temperature. The print head passes over the paper three times, providing the appropriate temperature for each color layer as needed.

Out of all of these incredible technologies, inkjet printers are by far the most popular. In fact, the only technology that comes close today is laser printers.

So, let’s take a closer look at what’s inside an inkjet printer.

Paper feed assembly:

  • Paper tray/feeder – Most inkjet printers have a tray that you load the paper into. Some printers dispense with the standard tray for a feeder instead. The feeder typically snaps open at an angle on the back of the printer, allowing you to place paper in it. Feeders generally do not hold as much paper as a traditional paper tray.
  • Rollers – A set of rollers pull the paper in from the tray or feeder and advance the paper when the print head assembly is ready for another pass.
  • Paper feed stepper motor – This stepper motor powers the rollers to move the paper in the exact increment needed to ensure a continuous image is printed.
  • Power supply – While earlier printers often had an external transformer, most printers sold today use a standard power supply that is incorporated into the printer itself.
  • Control circuitry – A small but sophisticated amount of circuitry is built into the printer to control all the mechanical aspects of operation, as well as decode the information sent to the printer from the computer.
  • Interface port(s) – The parallel port is still used by many printers, but most newer printers use the USB port. A few printers connect using a serial port or small computer system interface (SCSI) port.

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