Day 25. Printer Technologies and Maintenance

Objective 1.15: Given a scenario, perform appropriate printer maintenance.

Speed is measured in characters per second (CPS). Common speeds are 32 CPS–72 CPS. In newer models, 100–600 characters per second are not uncommon. Paper can be single sheets, multipart forms, or continuous feed. The closer the print head is to the paper, the stronger the strike and the darker the print. Continuous feed is enabled by the use of a tractor-feed mechanism.

The printer works by sending the print head continuously moving back and forth across the page, using tiny metal pins or wires to produce one line of text at a time. They are cheap in terms of costs but are loud and extremely slow. They are most valued for their ability to print to a continuous feed of paper and their ability to print to multipart forms.

Printing, ribbon costs, and maintenance are low

Continuous paper is possible

The inked ribbon fades out slowly

Can tolerate dirty and hot conditions

Very robust, lasting for years

Loud

Slow speed

Pins are easily bent

If print head fails, the entire printer must be replaced

Print head itself can become very hot

Laser printers move paper through the printer via motorized rollers. Most of the activity occurs within the toner cartridge, not the printer itself. Heaters fuse the toner onto the paper as it leaves the printer.

This type of printer has a chip called the raster image processor (RIP) that is used to translate a raster image into commands the printer can use. In other words, it is translating the data received in a format like a Word document or PDF file into a bitmap or raster image.

The raster image of the page shows what the final printout looks like. Because a laser printer needs to process a page at a time as an image, it is considered a page printer. In other words, the laser has to paint the entire surface of the drum before it can transfer the image to paper. That means it must have the entire page before beginning to print. If the printer does not have enough memory for the job, an error occurs.

Resolution for lasers is typically measured in dots per inch (dpi). Horizontal dpi is listed first with vertical dpi second. Typical dpi is 600×600 or 1200×1200. Horizontal dpi is determined by the physical characteristics of the printer and the size of the dots. Vertical is determined by how quickly the drum moves the paper through the printer. Using resolution enhancement technology (RET), a laser can insert smaller dots at the edges of characters and pictures providing a much cleaner print.

Toner cartridge—Includes the toner hopper, doctor blade for precise amount of toner, developer or magnetic roller, waste bin, wiper blade, primary charge roller, organic photo-conductor aluminum drum, and drum shutter to avoid exposure to light

Imaging drum—Included in the toner cartridge, it is an aluminum cylinder and should not be exposed to light

Fuser assembly—Heated rollers that fuse the toner to the paper

Erase lamp—Exposes the drum to light, neutralizing the electrical charge

Primary corona or charge roller—Included in the toner cartridge, it charges the photosensitive drum

Laser—Is the writing or painting portion of the printer

Transfer corona/roller—Outside the toner cartridge, this is a thin wire that charges the surface of the paper just before it reaches the toner area; newer models use a roller

Pickup rollers—Picks up the paper and feeds it to the printer

Logic circuits—The main processor, memory, firmware, and NIC card; advanced models may have a hard drive and secondary cards for finishing, such as duplexing, stapling and so on

Separate pads—Bars that rub against the paper as it is picked up to prevent more than one piece of paper to be picked up at one time

Duplexing assembly—An accessory that provides double-sided printing

RAM—Random access memory built in to the printer, usually upgradable

Figure 25-2 shows how each of the parts in a laser printer interacts with the other parts and where in the printer each of the processes takes place.

The following list details each step in the laser printing process.

Step 1: Processing—The computer sends the data to the printer.

Step 2: Charging—The primary corona wire is used to provide a uniform negative charge (between -600 and -1000 volts) to the surface of the drum.

Step 3: Exposing—The laser paints a positive image of the printout on the surface of the drum.

Step 4: Developing—Negatively charged toner attaches to the painted area.

Step 5: Transferring—The transfer corona wire (also called the secondary corona) charges the paper with a positive charge so that the negatively charged toner is pulled to the positively charged paper.

Step 6: Fusing—Two rollers, a heated roller and a pressure roller, are used to fuse the toner to the page. A static charge eliminator then removes any leftover charge from the drum, and the paper is ejected from the printer.

Step 7: Cleaning—The drum is cleaned of excess toner and electrical charges by a rubber cleaning blade.

High-volume efficiency

Speed

Quiet

Printout is dry

Large, take up space

Dangerous to the atmosphere and health

High maintenance and service costs

The print head scans the page and prints both forward and backward in vertical rows that might or might not handle a line of text. Print resolution is determined by how densely the nozzles lay ink on the page. Speed is determined by the frequency the nozzles are able to fire ink drops and the number of pages printed per minute (ppm).

Print head—Contains the nozzles that are used to spray drops of ink

Print head board—Includes the metal rail, ribbon cable, print cartridges, control switches, and LED display lights and moves them across the paper

Ink cartridge—Holds the ink

Roller—Pulls the paper in from the tray and advances the paper as it completes the printing process

Feeder—A stepper motor that powers rollers to move the paper in exact increments

Carriage and belt—A carriage assembly that holds the ink cartridges and uses a belt to move them back and forth across the page

Ribbon cable—Carries instructions from the electronic circuit inside the printer to the cartridges

Spiked wheel—Helps to grip the paper and move it through the printer

Duplex assemblies—Used to automatically print on both sides of the paper

Relatively high-quality printout

Can use plain paper or special-purpose paper

Color printing

Easy to use

Small footprint, easy to move around

Quieter than a dot matrix

Speed

Print head less durable, prone to clogging

Not designed for high-volume printing

Paper affects printout

Ink is sensitive to water

Longer life because it has fewer moving parts

Easy to use

Quiet

Paper must be stored at room temperature

Color not available

When hot, it uses more ink

Poor output quality

Wet ink

Four types of virtual printing are typical methods that can be accessed within an application:

Print to a file—Select the Print to a File option.

Print to XPS—The XML Paper Specification print path, it improves and speeds up color printing. It is an alternative to PDF introduced in Vista. Select Microsoft XPS Document Writer to save to an .xps file.

Print to PDF—The PDF converter must be installed along with Adobe Reader.

Print to an image—Utilizing the Print Screen key, an image of anything on the screen can be captured. Screen capturing programs such as the Windows Snipping Tool and Snagit from TechSmith can be used instead of the Print Screen key.

Figure 25-3 shows an image of a printer preferences utility with Print to File selected.

Another type of virtual printing is cloud printing. The printer can be at any location, reachable through the Internet. Google Cloud Print provides the ability to send print jobs to a printer from anywhere.

Figure 25-4 shows a print job being sent from a smartphone to the Cloud.

Serial—RS-232 (DB9M)

Parallel—IEEE 1284 (DB25F); Centronics port or cable

USB—Universal serial bus (versions 1, 2, and 3)

FireWire—IEEE 1394 High Performance Serial Bus (Apple)

Wireless—Infrared or Bluetooth

The following list covers the connections computers use when connecting to a printer using a network (network printer):

Ethernet—100Base-T, 1000Base-T, twisted-pair (TP) cables, and RJ-45 connectors

Wireless—Wi-Fi (802.11), infrared, or Bluetooth

Figure 25-5 shows some of the printer connection types.

Cleaning: Several tools are available to use when cleaning a printer (be sure to unplug the printer before cleaning):

Compressed air

Computer vacuum, which is electrostatic discharge (ESD) safe

Isopropyl alcohol, which is used on platens

Lint-free cloth

Cotton swabs

Small brushes, which are used to eliminate dust

Replacing: Inserting a new ink cartridge or ribbon can solve many problems with printouts. Replacing worn-out parts is another method that can lengthen the service life of a printer.

Updating: Updating printer drivers can provide new features and fix problems with drivers that have become corrupted. Upgrading the paper used can be a factor in maintenance.

Environment: Printers generate heat, so ensure that the temperature and humidity are kept at acceptable levels. Ink and paper should be kept in cool, low-humidity, dust-free environments.

Replacing consumables for an impact printer covers replacing the ribbon when it is worn out and the ink is light on the page. It also requires replacing the paper.

Static eliminator strips need to be changed when paper starts sticking before being ejected, more than one sheet of paper is being pulled through at a time, or the paper is being crumpled. If the ink smears on a printout from a laser printer, check the fuser assembly.

Replaceable parts include the fuser assembly; transfer rollers; separation pads; pickup rollers; and all the components that reside in the printer cartridge itself such as the drum, primary corona, cleaner blade, and toner.

Inkjet manufacturers usually include maintenance and diagnostic utilities with their drivers that provide services. They include some of the following:

Clean the print heads.

Adjust printing alignment.

Calibration.

Clean ink cartridges.

Clean the printer.

Perform diagnostics.

Check the nozzles.

Replacing the ink cartridges is usually relatively easy. Follow the manufacturer’s instructions because each printer is different. Many printers also give you an estimate on how much ink is left in each cartridge so you know when to replace them.