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How Inkjet Printers Work: A Look at the Components

Inkjet printers are all around us and used every day to create a vast array of projects from important documentation to photographs taken just prior. An inkjet printer works by creating extremely small droplets of ink and jetting them onto a substrate or surface passing through the printer. The jet of ink droplets is guided by a series of nozzles contained in printheads and release to create a specific pattern based off layouts given to the printer from a computer or other digital device. Small electrical impulses will trigger the ink cartridges to release or eject ink at the appropriate times, forming dots onto the media and eventually creating images and texts. The inkjet printer will be able to handle simple layouts such as text documents and extremely complex layouts that have details challenging resolution capabilities. Inkjet printers are the most common type of household printer because they generally have a quiet operation and can produce photograph quality results.

What components are needed and how do they work?

Inkjet printers have a lot of internal components that affect the overall quality, speed, reliability, and durability of the printer and its ink cartridges. To better understand how the printer works, an understanding of what components are needed, what their functions are, and how they interact with each other is needed.

The Ink Cartridge

Ink cartridges or inkjet cartridges are the starting point and most recognized component in an inkjet printer, as they are the only component that must be replaced when the ink runs out. There are several different types of ink cartridges and they vary greatly depending on the printer model and manufacturer intended for. Ink cartridges can contain black ink only, black and color ink in a single cartridge, just color inks in a single cartridge, or separate cartridges for each individual color. Many photograph printers will even have light cyan and light magenta cartridges to provide life-like tonality on photograph printouts. The main purpose of the ink cartridge is to house the colorant or ink, until being released into the printheads.

Printheads

The Ink cartridges are directly connected with printheads or contain their own printheads built-into the cartridge. The Printhead is where all the magic happens inside the machine and is the component responsible for guiding the ink onto the page. A printhead consists of a series of tiny nozzles that are used to jet out or spray the aqueous ink solution from the cartridges to the piece of media passing through the printer.

When separate from the ink cartridges, printheads are the component that you snap the ink cartridges into when replacing ink. They look a lot like a trough or sunken in bench with small round protrusions arising into the ink cartridges. The round protrusions will insert into the cartridges when snapping them into place opening a passageway for the ink to travel down during the printing process.

An ink cartridge that contains its own printhead will rest at the bottom of the cartridge and looks like a computer chip or smoothed metal contact filled with tiny circuits and groves. Both printheads, separate and included, are responsible for letting the cartridge know when and where to release the ink.

Control Circuitry

In order to figure out the precise mathematics of when to release ink and when to hold back ink, a Control Circuit is interposed between the printer driver from the host computer and the printer itself. The circuit will actually control where energy is distributed amongst the chip and where to remove current flow. This will cause the ink cartridge to open or close particular nozzles to either start jetting ink out or to stop the flow of ink.

The printer driver on the host computer will translate images and text documents into a mathematical map or grid known as bitmap. The process of translating the images from a computer to a grid is known as the Raster Image Process. This lets the printhead Control Circuit know when to energize a specific spot on the circuit, releasing the ink and when to de-energize an area to stop the flow.

Stepper Motors

A Stepper Motor will rapidly move the printheads and the ink cartridges back and forth inside the machine and across the width of the media passing over every portion of the paper.  The Stepper Motor also has a secondary job of putting the rollers in motion during the printing process. This is achieved in a number of ways from belts to meshing gears, a common way to get multiple parts moving. The purpose of the Stepper Motor is to transform received electrical power into motion, which is basically making the internal components move.

Stabilizer Bar

Included with the printheads is a Stabilizing Bar that evenly distributes force on the printheads when they are in motion, moving quickly back and forth along the media. As the printheads and ink cartridges rapidly move back and forth, the inner particles are pulled from one side to the other. Similar to being in a car that is taking a sharp turn, the centripetal force will push you to one side of the vehicle. The Stabilizing bar helps to keep the cartridges at a steady angle to eliminate or reduce this effect. This will help keep the ink formulations from clotting or collecting in one location of the cartridge. 

Belt

A belt is also one of the components found inside an inkjet printer. Just like the belts used in car motors, the printer belt is used to rotate additional parts. A belt is generally banded to a rotating component on a motor and stretched to wrap around other components that need to rotate. When the motor is powered on, a magnet will rapidly start rotating inside the motor causing external components on the motor to also spin or rotate. The belt uses the spinning force of the motor to spin or rotate the other parts that need to move.

In the inkjet printer, the belt is connected to the printhead assembly from the stepper motor, in order to move the ink cartridges back and forth inside the machine. Belts can also be used to assist the rollers found inside printers.

Rollers

The purpose of the rollers is very simple. They are used to carry or drive a piece of media (usually paper) through the printer. The rollers will grab a piece of media from the top of the stack placed inside the designated Input Tray and will transport that piece of media underneath the printheads and ink cartridges before ejecting the finished printout to the Output Tray. Some office inkjet printers that have Automatic Duplex capabilities can even have rollers that drive the media back through the printer to expose the reverse substrate underneath the printheads to create two-sided printouts.  

Paper Trays

Another very recognizable component of the printer is the Paper Trays. Typically Inkjet printers will have a single Input Tray located at the top or back of the printer and a single Output Tray located in the front of the machine. Another common tray configuration is to have the Input Tray and Output Tray conflated into a single front-feeding tray. When both are used as one tray, such as with the HP PSC series printers, the tray will usually have small mounting members on either side of the tray to elevate the printed material from entering back through the printer. These also act as guides when loading new media into the Tray and as a divider between the Input and Output sections of the tray.

Power Supply

To supply power to the stepper motor and control circuitry a standard power supply has been incorporated into the printer. The purpose of the power supply is to convert the alternating current (AC) from a wall outlet to more controllable direct current (DC), needed to operate the stepper motors and circuitry inside printers. The power supply is also responsible for lighting up and energizing additional features such as display screens and scanning equipment.  

Interface Ports

Also included with inkjet printers are ports that allow users to connect and transfer digital data between devices. The most common printer interface is the Hi-Speed USB 2.0 port which was created to outperform the older IEE Parallel interfaces. The Hi-speed USB 2.0 ports also broaden the range of external peripherals or devices that can be connected with the printer. The Interface ports main purpose is to provide a means to transfer data (usually text documents and images) from the computer to the printer and vice versa.

Photograph inkjet printers will typically have compatible media card slots as well, that allow users to walk-up and plug media cards and flash drives directly into the printer to print the files and photographs on the card without needing a computer.

These are the main components that can affect the output quality, durability, and performance of an inkjet printer and its ink cartridges. Hopefully this will help you identify and possibly prevent or fix any issues that are occurring with your machine. 


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