Inside an Inkjet Printer
Parts of a typical inkjet printer include:

  • Print head assembly
    • Print head - The core of an inkjet printer, the print head contains a series of nozzles that are used to spray drops of ink.

The print head assembly

    • Ink cartridges - Depending on the manufacturer and model of the printer, ink cartridges come in various combinations, such as separate black and color cartridges, color and black in a single cartridge or even a cartridge for each ink color. The cartridges of some inkjet printers include the print head itself.
    • Print head stepper motor - A stepper motor moves the print head assembly (print head and ink cartridges) back and forth across the paper. Some printers have another stepper motor to park the print head assembly when the printer is not in use. Parking means that the print head assembly is restricted from accidentally moving, like a parking brake on a car.

Stepper motors like this one control the movement of most parts of an inkjet printer.

    • Belt - A belt is used to attach the print head assembly to the stepper motor.
    • Stabilizer bar - The print head assembly uses a stabilizer bar to ensure that movement is precise and controlled.

Here you can see the stabilizer bar and belt.

  • 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.

The rollers move the paper through the printer.

    • 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.

The mechanical operation of the printer is controlled by a small circuit board containing a microprocessor and memory.

  • 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.

While USB taking over, many printers still use a parallel port.