The Clickinks Blog | drum unit

How does a Laser Printer Work?

22. January 2011 06:00 by Danielle Bernhard in clickinks, drum unit, laser toner cartridges, laserjet, remanufactured toner  //  Tags:   //   Comments (0)
You may have a Laserjet printer, or have at least used one, but do you really know how a laser printer works?

In the beginning, the first printers attached to computers were impact printers, typically dot matrix. Everyone understood how these devices worked, as they functioned just like the electric typewriters of the time. A hard object struck an ink ribbon with enough force to transfer the ink onto the page. As technology evolved, along came the next generation, which included inkjet and laser printers. The inkjet printer works just like the name implies; an image is put on the paper by using microscopic jets of ink. The laser printer, on the other hand, is a bit of a mystery. How can a highly focused beam of light impart letters and images on a piece of paper? Is the laser inside my printer dangerous?

Following are the six key processes that happen inside a laser printer when you click print.

Charging: A charge roller (or corona wire in older machines) will project an electrostatic charge onto the photoreceptor. This is a revolving drum or belt which is capable of holding an electrostatic charge on its surface as long as it hasn't been exposed to wavelengths of electromagnetic radiation (and will be referred to as drum for the rest of this article).

Writing: A processor chip converts information for scanning onto the drum. The laser is aimed at a series of lenses and mirrors onto the drum. Lasers are used because they generate a coherent beam of light for a high degree of accuracy. Wherever the laser strikes the drum, it reverses the charge, thus creating a latent image on the surface.

Developing: The surface containing the latent image is exposed to toner, which is very fine particles of wax or plastic mixed with coloring agents. The charged toner particles are electrostatically attracted to the drum where the laser wrote the latent image.

Transferring: The drum is pressed or rolled over paper, transferring the image. Higher end machines use a positively charged transfer roller on the back-side of the paper to pull the toner from the photoreceptor to the paper.

Fusing: The paper passes through a fuser assembly, which has rollers that provide heat and pressure that bonds the toner to the paper.

Cleaning: When the print is complete, an electrically neutral rubber blade cleans any excess toner from the drum and deposits it into a waste reservoir, and a discharge lamp removes the remaining charge from the drum.

Each printer applies these steps in different ways. Most laser printers today actually use a linear array of light-emitting diodes to write the light on the drum. The toner is based on either wax or plastic, so that when the paper passes through the fuser assembly, the particles of toner melt. The paper may or may not be oppositely charged. The fuser can be an infrared oven, a heated pressure roller, or a xenon bulb. The warm up process that a laser printer goes through when power is initially applied to the printer consists mainly of heating the fuser element. Many printers have a toner-conservation mode which uses less toner but does yield prints with lower contrast. Color laser printers add colored toner in three additional, yet identical, processes.

So you now know that when you print that document, you are safe from a wayward laser beam melting a hole in your monitor and when it is time to get a replacement for that laser toner cartridge, you need to go to ClickInks.com. With your purchase of our remanufactured toner cartridges, you help reduce the amount of cartridges that are disposed of into landfills and save yourself money at the same time.

The Home and Business Printer Glossary

Have you ever shopped for a printer wondering if you should pay extra for “PictBridge”? Shopped for an ink cartridge and gotten confused by the difference between “OEM” and “Remanufactured Cartridge”?  Or spoken to a graphic designer and felt clueless what the “pantone” in your print job was?  In an effort to assist with all your printer needs, we have assembled this Printer Glossary below.  Feel free to print and bookmark for reference.

All-in-One (AIO) - This is a multifunction printer that can also scan and copy. Many of these devices can send and receive faxes as well. These are sometimes referred to as multi function printers.

Anti-Aliasing - The process of removing or reducing the jagged distortions in curves and diagonal lines so that lines appear smooth or smoother.

Auto Answer - This is a setting on most fax machines, fax modems and multifunction devices with fax capability. With auto answer, the device automatically picks up incoming fax calls after a specified number of rings.

Automatic Document Feeder - A tray and/or attachment that feeds one page at a time into a fax, copier, printer, or scanner.

Bit - The abbreviation for binary digit; the smallest unit of digital information, represented by 1 or 0. Computers use many bits to represent information.

Bit Depth - A digital image is represented as a bit-map (a grid of dots). Bit Depth is the number of color tones that can be associated with each dot. A 1-bit color, for example, can only contain 2 colors: black and white. But an 8-bit color contains 256 shades (color or gray), while a 24-bit color contains 16.7 million shades.

Bitmap File - The standard graphics format carries the file extension .BMP.

Borderless Printing - Printing photos with no white space around the edges. Borderless prints look like the high quality prints from a photo lab.

Brightness - An adjustment to control the lightness and darkness of an image, measured by the percentage of reflected light.

Broadcast Faxing - A fax machine feature found on most all-in-ones that sends the same fax documents to multiple recipients.

Carriage - The fixture in the print device that holds the print head. Generally travels along carriage rods from side to side.

Central Processing Unit (CPU) – This is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. The central processing unit carries out each instruction of the program in sequence, to perform the basic arithmetical, logical, and input/output operations of the system.

Centronics - A pioneering American manufacturer of computer printers now remembered primarily for the parallel interface and printer cable that bears its name. These cables are often referred to as Centronics cables.

Charging Roller - One of the complex systems of rollers inside a typical laser printer or all-in-one. The charging roller transfers an electrical charge to the photo conductor, which repels particles to the toner.

CMYK - An acronym to represent cyan, magenta, yellow and black, the basic colorants (dyes, pigments or toners) used in digital imaging. These four colors alone are used to create all colors in an image.

Collation - A feature offered on some inkjet printers, laser printers and all-in-ones. With collation turned on, multiple copies of a document are printed as separate documents.

Compatible Cartridges - A brand new printer cartridge that is made by a third party, not the OEM by the original printer manufacturer.  Compatible cartridges are widely known as a trusted, affordable option.

Contrast Enhancement (Automatic) - Automatically brightens images that appear dark or hazy, and applies appropriate tone correction to deliver improved quality and clarity.

Corona Wires - A set of thin wires inside the body of a laser printer that transfers a static charge to each sheet of paper; this charge in turn attracts the toner to the paper.

Dedicated Print Server - A computer in a network dedicated to managing all available printers.

Dot Matrix - An older impact printer that used a grid of tiny pins to transfer ink from a ribbon to the page. Dot matrix printers can produce basic graphics, but have inferior print quality compared to inkjet or laser printers.

Dots Per Inch (DPI) - A measurement of print resolution. DPI indicates how many individual dots a device can address on a page per square inch of area. DPI is typically listed as horizontal resolution by vertical resolution.

Driver - Software that comes with a peripheral that allows the peripheral to communicate with the computer.

Duplex - Printing both sides of a two-sided document on a single sheet of paper.

Drum unit - The photoreceptor in a laser printer which is electrically charged, rotating and  coated with organic photo conductors.  The drum picks up toner and then prints the image onto paper by direct contact and heat, which fuses the ink to the paper.

Enhanced Capability Port (ECP) - This is an international specification describing bidirectional communications using a computer's parallel port. ECP focuses on printers and scanners.

Enhanced Parallel Port (EPP) - An international standard documenting bidirectional communications using a computer’s parallel port. EPP focuses on peripherals other than printers and scanner.

Ethernet Network - The simplest, slowest and least expensive network design, usually well-suited for home or small offices.

Fax Forwarding - A fax feature that enables the machine to automatically forward any document it receives to another fax.

Fax Header - An informational line of text printed at the top of every page by a fax machine; it includes a name, station ID and fax number.

FireWire - High-speed external connection used for connecting peripherals, also referred to as "IEEE 1394".

Firmware - Low-level software that runs in a digital camera, printer, scanner, etc. and controls the product's operation and user interface.

Font - A set of printing characters that share the same distinctive appearance. Fonts are used on a computer to display text on the monitor and print documents.

Fuser Roller - One of a system of rollers inside a laser printer. The fuser roller heats the page after the toner is applied, so the toner partially melts and sticks to the page for a permanent bond.

GIF Image - Short for Graphics Interchange Format; usually carries the file extension .GIF. The first truly universal standard format for file images, originally developed by CompuServe. Widely used on the web, GIF files are best used for small images in limited colors.

IEEE-1284 Standard - The international design specification for bidirectional parallel printer cables. Most inkjet and laser printers do not work properly unless the printer cable meets this specification. Most products now use USB for printer-to-computer communication.

Impact Printer - A class of printer that uses the force of an impact into an ink ribbon to create a printed character on a page. This impact is delivered by a rotating ball or wheel or through a grid of pins. This type of printer is generally slow, noisy and out-dated. These printers are useful for multipart forms such as invoices or shipping bills.

Individual Ink Cartridges (IIC) - Some inkjet manufacturers printing solution that has a different ink cartridge for each color.

InfraRed (IR) - This is a type of connection that allows data to be wirelessly transmitted from one device directly to another device when the infrared window on the camera is lined up with an infrared sensor on the other device. This technology is similar to what most TV remote controls use.

Inkjet Cartridge - An inkjet cartridge is a replaceable component of an inkjet printer that contains the liquid ink (and sometimes a print head, micro-chip and other technology and moving parts).


Inkjet Printer - A printer or an all-in-one unit that shoots fast-drying ink through tiny nozzles onto a page to form characters. The inkjet is currently the standard for personal computer printing. Inkjets are fast, affordable and quiet. They provide high-quality graphics and print in color.

Input/Output Card - Usually abbreviated I/O card. A standard computer adapter card that typically provides two serial ports for your modem and two parallel printer ports.

Interrupt Request - Usually abbreviated IRQ. A signal generated by an adapter card in the computer that alerts the CPU to handle incoming data from the keyboard, mouse, serial port or parallel port.

JPEG File - Usually carries the file extension .JPG. The current favorite image format among web surfers and graphics professionals, JPEG images are highly compressed to save more space than a .BMP or .GIF file.

Label Stock - A paper sheet carrying peel-off or perforated labels that are arranged in a specified pattern.

Landscape Printing - Printing where the longer length of the page runs from side to side rather than top to bottom. Landscape mode is often used to print spreadsheets and larger photographs.

Large-format Printer - An inkjet printer designed to handle paper sizes of 11x17 inches or larger. Some large-format printers also use continuous rolls of paper. These printers are generally designed to produce photo-quality posters, blueprints, maps, banners and signs.

Laser Printer – This is a device that uses static electricity and heat to bond particles of toner to the page to create the characters. This is the same technology used by many copy machines and is known as a best option for large businesses.

Local Area Network (LAN) - A group of computers in an office or building connected to one another by cabling. A network computer can access files on other computers in the network or enable others to open and use its files. Printers, modems and hard drives are also typically shared peripherals on a network.

Media - The material that the ink is printed upon, such as plain paper, mailing labels or transparency film.

Monochrome Printer - A printer that prints in only one color, usually black. Some monochrome printers can also produce text and graphics in shades of gray, as well as strict black-and-white.

Network Interface Card (NIC) - An adapter card installed in a computer that enables it to connect to a network; most NICs support several different types of networks and network cabling.

Network Printer – This is a printer available for use by all of the workstations on a network. A network printer either has its own built-in network interface card or it is connected to a printer server on the network.

Original Equipment Manufacturer (OEM) - Products or components that are manufactured or purchased by a company and retailed under that company's brand name.

Page Description Language - A language recognized by computers and printers that define the physical characteristics of a page, including fonts, graphics, margins, spacing and colors.

Page Memory - The number of pages a fax can hold in its memory if it runs out of paper.

Pages Per Minute (PPM) - A measurement of printer speed, indicating how many finished pages a printer can produce over a 60 second period. PPM speeds are typically listed for both black-only and mixed text and color documents.

Page Storage – This is the number of pages (text or graphics) that can be stored internally on the given device.

Pantone - A color matching system supported by most desktop publishing and graphics design software.

Paper Capacity - Refers to how much paper the printer tray can accommodate.

Paper Guides - Adjustable plastic dividers that help hold paper in the proper alignment in a printer's paper feed tray. These guides can be moved to fit different dimensions, such as international sizes, envelopes or custom-sized paper.

Parallel Port - This is the common name for one type of printer connector on the back of a typical computer. I/O adapter cards are available that can provide a computer with up to four separate parallel ports, but most computers come with one as standard equipment.

Peripheral - This is a device attached to a host computer, but not part of it, and is more or less dependent on the host. It expands the host's capabilities, but does not form part of the core computer architecture.

Peer-to-Peer Network - A simple network design that uses no file or printer servers. All workstations on the network are connected by cabling, which enables users to share files and hardware, such as printers.

PictBridge - PictBridge allows digital cameras, camcorders and other image-capture devices to connect and print directly to photo printers and other output devices; no computer is required.

Pixel - A single element within a digital photograph. The typical digital photograph is made up of several million pixels.

Port Connection - A communication link between hardware components. Types of connections include FireWire, Parallel, USB, Serial, and SCSI.

Port Polling - A procedure performed by Windows® each time the computer is booted and each time a print job is sent from an application. The operating system automatically checks the parallel port to make sure that a printer is ready to receive a print job. In many cases, port polling can be turned off to improve printing speed.

Print Buffer - A separate, standalone print spooler with its own built-in memory that connects a computer and printing hardware. The print buffer can spool print jobs, freeing up all of a computer's resources for applications.

Printer Cartridge - The device that integrates the print head, ink container and ink delivery systems.  A printer cartridge may contain ink or toner.

Printer Driver - The software that enables the operating system to properly build and format commands and data bound for the printer; in effect, a printer driver tells the operating system all it needs to know to successfully operate the printer.

Printer Emulation - This is software that enables a newer printer to act like an older, widely used printer so it can recognize and print documents formatted for that older model.

Printer Server - A computer solely dedicated to supporting a network printer. The server's system RAM and hard drive are used to store print jobs in the queue, and print jobs can be reordered, paused, or deleted from the server's keyboard.

Print Head - This is the element of a printer that applies the ink to the paper. In an inkjet device, the print head contains the nozzles and electronics that control the ejection of the ink onto the selected media.

Print Quality - A qualitative description of how pleasing printed output looks. Most printers enable the user to adjust the quality of print and the speed of printing. In general for inkjet printers, slower print speeds will result in higher print quality.

Print Resolution - The quantity of data capable of being printed, typically measured in dots per inch (DPI). Higher resolution is one of many factors that can improve print quality.

Queue - A sequence of documents sent to a printer to be processed sequentially, usually in the order in which they were sent by the computer.

Remanufactured Cartridge - ClickInks.com’s remanufactured cartridges are made from recycled cartridge cores. Each cartridge is cleaned, inspected and refilled to conform to strict ISO 9001 quality standards and meet or exceed OEM specifications. Remanufactured cartridges from ClickInks.com contain the same amount of ink or more as the OEM ink cartridges, and print the same number of pages.  Remanufactured cartridges are widely recognized as a more affordable and environmentally friendly option, keeping empty cartridges out of landfills

Serial Port - This is the common name for one type of printer connector on the back of a typical computer. This is a physical interface through which information transfers in or out one bit at a time.

Small Computer System Interface (SCSI) - Set of standards for physically connecting and transferring data between computers and peripheral devices.

Thermal Dye Sublimation - In dye-sublimation printing, the dyes vaporize and permeate the glossy surface of the paper before they return to solid form, creating a gentle gradation at the edges of each pixel. The color infuses the paper and is less vulnerable to fading and distortion over time.

Tri-Chamber Cartridge – This is a descriptive term for a singular inkjet cartridge that contains all three colors of ink; cyan, magenta and yellow (CMY).  Often marketed as a tri-color cartridge.

Universal Serial Bus (USB) - A fast input/output (I/O) data transfer standard used for connecting peripherals to a computer. Typically, each device connected to a computer uses its own port. USB can connect up to 127 peripherals through a single port, and peripherals can be connected together. USB devices may be hot swapped, which means that power does not have to be turned off to connect or disconnect a peripheral. USB has become the primary means of connection for printers and other peripherals, and is supported by most major hardware, software and telecommunications providers.

The ABC's of Laser Printers

ASSEMBLY – A Laser Printer is great to have, especially in an office. Know your printer, and know what you are purchasing. Some laser printers include an all-in-one drum and toner assembly, which can be easier to use if you run a smaller office. Most large office printers will use a separate drum cartridge, which will save you in the long run.

BREAKAGE – Learn to avoid breakage by following these simple steps:

Use the correct paper for your printer, make sure that it is intended for a Laser Printer to avoid jams and achieve the best print quality.

If you hear any weird noises, stop. Look for error lights and assure the toner is inserted correctly and has clicked into place.

CARTRIDGE - When running low on toner it is common to shake the cartridge, but do not take those office aggressions out on it, a light shake with no rocking is all that is needed.

If you encounter smears or streaks on your print out, you may need to replace the drum. If you print nothing but a blank page, you may need a new toner cartridge.

If toner powder spills in your printer vacuum out or clean with a dry cloth before printing.

One last Acronym for you: R.T.M. – Read The Manual.

How To Replace The Drum Unit In Your Laser Printer

Did you know the drum unit of your laser printer is separate from the toner cartridge? Like the toner, it occasionally needs replacing – at which time your printer LCD display may read ‘Change Drum Soon.’ However, if your printer doesn’t have an LCD display, you’ll know the drum unit needs replacing when prints have thick black spots, become blurry, or print out lighter than normal.

To replace the drum unit of your laser printer, please follow these simple steps:

1) If you’ve recently done printing, let the machine cool down. It gets hot!

2) Handle the drum carefully. It holds ink that can splatter!

3) Open the printer’s front cover.

4) If your laser printer includes a drum lever, flip it so that it’s vertical.

5) Pull the drum unit and toner cartridge assembly from the printer with the handle.

6) Hold the lock lever down on the assembly and remove the toner bin.

7) Take the new drum unit and remove the protective sheet.

8) Reinstall the toner cartridge into your new drum unit by sliding into place. If installed correctly, the lock lever will lift easily.

9) Slide your new assembly into the laser printer. It should snap into place.

10) Close the drum lock lever, if your laser printer comes equipped with one.

11) Close the top cover.

12) If your printer has an LCD display, press ‘Options’ then ‘Yes’ to ‘Replace Drum.’

13) Once the laser printer has finished recognizing the drum unit, you’re ready to print!

The old drum unit should be placed in a plastic bag. After that it can be recycled.