Home > Articles > Hardware

I/O Ports and Devices

This chapter is from the book

This chapter is from the book

Printing Fundamentals

There are four types of printers you should be aware of:

  • Laser
  • Inkjet
  • Thermal
  • Impact

The following sections introduce you to the basic features of each printer type:

  • How printers create a page (note in particular the steps used by a laser printer to create a page)
  • Major components of each printer type covered (thermal printers as well as impact, inkjet, and laser/LED)
  • Typical printer operation and output problems and their solutions
  • How printers are interfaced to the computer

Laser Printers

Laser printers are similar in many ways to photocopiers:

  • Both use an electrostatically charged drum to receive the image to be transferred to paper.
  • Both use a fine-grained powdered toner that is heated to adhere to the paper.
  • Both must feed the paper through elaborate paper paths for printing.

However, significant differences exist between the photocopier and its computer-savvy sibling:

  • Laser printers produce images digitally, turning individual dots on and off; most copiers, however, are still analog devices.
  • Laser printers work under the control of a computer; copiers have a dedicated scanner as an image source.
  • Laser printers use much higher temperatures than copiers to bond printing to the paper; using copier labels or transparency media in a laser printer can result in damage to the printer due to melted label adhesive, labels coming off in the printer, or melted transparency media.

One type of laser printer is the LED printer. LED stands for light-emitting diode, which the LED printer uses as its light source. The essential difference between a laser and an LED printer is in the imaging device. The laser printer uses a laser to transfer the image to the drum, whereas an LED printer uses an LED array to perform the same task. Otherwise, these technologies are practically identical.

Although the technology of laser printers is interesting, we cannot forget what they use to print and what they print on. Laser printers use toner cartridges that can be replaced when they are empty. These printers print their information best on paper that is optimized for laser printers. Let's discuss toner cartridges and laser printing paper now.

Toner Cartridges

Most monochrome laser printers use toner cartridges that combine the imaging drum and the developer with black toner. This provides you with an efficient and easy way to replace the laser printer items with the greatest potential to wear out.

Depending on the model, a new toner cartridge might also require that you change a wiper used to remove excess toner during the fusing cycle. This is normally packaged with the toner cartridge.

When you install the toner cartridge, be sure to follow the directions for cleaning areas near the toner cartridge. Depending on the make and model of the laser printer, this can involve cleaning the mirror that reflects the laser beam, cleaning up stray toner, or cleaning the charging corona wire or conditioning rollers inside the printer. If you need to clean the charging corona wire (also called the primary corona wire on some models), the laser printer contains a special tool for this purpose. The printer instruction manual shows you how to clean the item.

Keep the cartridge closed; it is sensitive to light, and leaving it out of the printer in room light can damage the enclosed imaging drum's surface. Figure 3-25 shows a typical laser printer toner cartridge and mirror cleaning tool. The tool above the toner cartridge is used to clean the printer's mirror.

Figure 3-25

Figure 3-25 A typical laser printer toner cartridge. The inset shows the mirror cleaning tool in use after the old toner cartridge has been removed and before the new cartridge is put into position.

Color laser printers differ from monochrome laser printers in two important ways: They include four different colors of toner (cyan, magenta, yellow, and black), and the imaging drum is separate from the toner. Thus, instead of waste toner being reused as in a monochrome laser printer that has a toner cartridge with an integrated imaging drum, waste toner in a color printer is sent to a separate waste toner container.

Depending upon the toner transfer technology used, a color laser printer might require four passes to print a color page (one pass per color), or only one pass to print all four colors.

Laser Printer Paper and Media

For best results with laser printing, use these guidelines when selecting paper and media:

  • Use paper made for laser or photocopier use. Extremely rough-surfaced specialty papers might not enable the toner to fuse correctly to the paper.
  • Use envelopes made for laser printing, especially if the printer doesn't offer a straight-through paper path option. Standard envelopes can lose some of their flap adhesive or have the flap stick to the back of the envelope when used in a laser printer.
  • Use only labels made for laser printers; these labels have no exposed backing, requiring you to separate the labels from the backing after printing.
  • Use only laser-compatible transparency stock; it can resist the high heat of the fuser rollers better than other types, which can melt and damage the printer.
  • Avoid using paper with damaged edges or damp paper; this can cause paper jams and lead to poor-quality printing.
  • Load paper carefully into the paper tray; fan the paper and make sure the edges are aligned before inserting it.

Inkjet Printers

Inkjet printers (also known as ink dispersion printers) represent the most popular type of printer in small-office/home-office (SOHO) use today and are also popular in large offices. Their print quality can rival laser printers, and virtually all inkjet printers in use today are able to print both color and black text and photographs.

From a tightly spaced group of nozzles, inkjet printers spray controlled dots of ink onto the paper to form characters and graphics. On a typical 5,760x1,440 dots per inch (dpi) printer, the number of nozzles can be as high as 180 for black ink and more than 50 per color (cyan, magenta, yellow). The tiny ink droplet size and high nozzle density enables inkjet printers to perform the seemingly impossible at resolutions as high as 1,200dpi or higher: fully formed characters from what is actually a high-resolution, non-impact, dot-matrix technology.

Inkjet printers are character/line printers. They print one line at a time of single characters or graphics up to the limit of the printhead matrix. Inkjet printers are functionally fully formed character printers because their inkjet matrix of small droplets forming the image is so carefully controlled that individual dots are not visible.

Larger characters are created by printing a portion of the characters across the page, advancing the page to enable the printhead to print another portion of the characters, and so on until the entire line of characters is printed. Thus, an inkjet printer is both a character and a line printer because it must connect lines of printing to build large characters. Some inkjet printers require realignment after each ink cartridge/printhead change to make sure that vertical lines formed by multiple printhead passes stay straight; with other models, alignment can be performed through a utility provided as part of the printer driver when print quality declines due to misalignment.

Ink Cartridges

Many inkjet printers, especially low-cost models, use a large tank of liquid ink for black and a separate tank with separate compartments for each color (typically cyan, magenta, and yellow; some models feature light versions of some of these colors for better photo-printing quality). However, the trend in most recent models has been to use a separate cartridge for each color. This improves print economy for the user because only one color at a time needs to be replaced. With a multicolor cartridge, the entire cartridge needs to be replaced, even when only one of the colors runs out.

Figure 3-26 shows some of the typical components of an inkjet printer.

Figure 3-26

Figure 3-26 A typical inkjet printer with its cover open.

Depending on the printer, the printhead might be incorporated into the ink tank; be a separate, user-replaceable item; or be built into the printer.

Some inkjet printers feature an extra-wide (more nozzles) printhead or a dual printhead for very speedy black printing. Some models enable the user to replace either the ink cartridge only or an assembly comprising the printhead and a replaceable ink cartridge.

An inkjet printer is only as good as its printhead and ink cartridges. Clogged or damaged printheads or ink cartridges render the printer useless. If an inkjet printer fails after its warranty expires, you should check service costs carefully before repairing the unit. Failed inkjet printers are often "throwaway" models and can be replaced, rather than repaired, even during the warranty period.

Always use the printer's own power switch, which enables the printer to protect the ink cartridges and perform other periodic tasks (such as self-cleaning) properly.

Inkjet Printer Paper and Media

Although papers made for copiers and laser printers provide adequate results, you must use inkjet-specific media of the following types to achieve best print quality:

  • Glossy photos
  • Transparencies
  • Business cards
  • Labels (especially clear labels)

It is also critical to use the correct print setting for the media type to avoid smudging, lines, and other print defects.

Thermal Printers

Thermal printers use heat transfer to create text and graphics on the paper. Thermal printers are used in point-of-sale and retail environments, as well as for some types of portable printing.

Thermal printers are available using three different technologies:

  • Thermal transfer
  • Direct thermal
  • Dye sublimation

Thermal printers can use a dot-matrix print mechanism or a dye-sublimation technology to transfer images. Some thermal printers use heat-sensitive paper, and others use an ink ribbon to create the image. Let's start by discussing the thermal printer ribbon.

Thermal Printer Ribbons

Thermal transfer printers use wax or resin-based ribbons, which are often bundled with paper made especially for the printer. The most common type of thermal transfer printer uses dye-sublimation (dye-sub) technology to print 4x6 continuous-tone photographs. Examples of dye-sublimation printers include Kodak printer docks and Canon's Selphy CP series.

Figure 3-27 illustrates a typical dye-sublimation ribbon for a Canon Selphy CP printer.

Figure 3-27

Figure 3-27 A dye-sublimation ribbon for a 4x6-inch photo printer (Canon Selphy CP).

Thermal transfer printers used in point-of-sale or retail environments typically use non-impact dot-matrix printheads.

Thermal Printer Paper

Direct thermal printers use heat-sensitized paper, and thermal transfer printers might use either standard copy paper or glossy photo paper, depending upon their intended use.

If the printer uses direct thermal printing, heat-sensitive paper with characteristics matching the printer's design specifications must be used. For portable printers using direct thermal printing such as the Pentax PocketJet series, the usual source for such paper is the printer vendor or its authorized resellers. If the direct thermal printer is used for bar codes or point-of-sale transactions, you can get suitable paper or label stock from bar code or POS equipment suppliers and resellers.

If the printer uses thermal transfer and is not designed for photo printing, most smooth paper and label stocks are satisfactory, including both natural and synthetic materials. However, dye-sublimation photo printers must use special media kits that include both a ribbon and suitable photo paper stocks.

Impact Printers

Impact printers are so named because they use a mechanical printhead that presses against an inked ribbon to print characters and graphics. Impact printers are the oldest printer technology, and are primarily used today in industrial and point-of-sale applications.

Dot-matrix printers, the most common form of impact printers, are so named because they create the appearance of fully formed characters from dots placed on the page.

Dot-matrix printers use a thermal or impact print head containing multiple pins that are used to form characters and graphics. Dot-matrix and other printers that print a line at a time are sometimes referred to as line printers. Typically, the term "page printers" refers to laser or LED array to change the electrostatic charge on a drum to attract toner, which is then transferred to paper to form the page.

The print mechanism of the dot-matrix printer is almost always an impact mechanism: A printhead containing various numbers of fine wires (called pins) arranged in one or more columns is used along with a fabric ribbon, similar to typewriter technology. The wires are moved by an electromagnet at high speed against the ribbon to form dot patterns that form words, special characters, or graphics. Figure 3-28 shows actual print samples from a typical 9-pin printer's draft mode, a typical 24-pin printer's draft mode, and the Near Letter Quality (NLQ) mode of the same 24-pin printer. The narrower pins of the 24-pin printhead produce a reasonably good NLQ printout but hard-to-read results in draft mode.

Figure 3-28

Figure 3-28 Actual print samples illustrating the differences in 24-pin and 9-pin impact dot-matrix printers.

Figure 3-29 illustrates a typical impact dot-matrix printer.

Figure 3-29

Figure 3-29 Components of a typical impact dot-matrix printer. The model pictured is a wide-carriage version, but its features are typical of models using either standard or wide-carriage paper.

Impact Printer Ribbons

Printer ribbons for impact printers use various types of cartridge designs. Some span the entire width of the paper, and others snap over the printhead. Figure 3-30 compares various types of ribbons for impact printers.

Figure 3-30

Figure 3-30 Some typical ribbons for impact dot-matrix printers.

Impact Printer Paper and Media

Impact printers use plain uncoated paper or labels in various widths and sizes. Impact printers designed for point-of-sale receipt printing might use roll paper or larger sizes of paper. When larger sizes of paper are used, these printers typically use a tractor-feed mechanism to pull or push the paper past the printhead. Paper used with tractor-fed printers has fixed or removable sprocket holes on both sides of the paper.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020