Laser printers are becoming increasingly popular among home and business users due to their ability to print faster than an inkjet printer. Laser printers might be more expensive, but the cost of maintenance is lower than inkjet printers.
Your printing needs will determine which printer you need.
How Laser Printers Work
Rasterizing an Image
When the printer receives a document, the driver translates the image for the printer, via the port connection. For the computer and the printer’s controller to communicate they need to “speak” the same language. There are two primary languages used in laser printers: Adobe’s Postscript and HP’s Printer Command Language (PCL). Each language describes everything on the page including fonts, graphics, spacing and colors. When the printer’s controller receives the data, the Raster Image Processor (RIP) will then break down all the information into a raster image or into a series of dots.
To create the image on the photoreceptor drum, first a corona wire or a charged roller, will give a positive electrostatic charge to the drum. As the drum rotates, the laser “draws” the raster image across the drum by creating a pulse of light for each dot of the image. Each pulse of light is altering the electrical charge of the drum.
Once the page is created, the toner is coated onto the drum. First, the developer unit moves through the toner. Because the developer unit has a negative charge, it picks up the positively charged toner. The developer then passes through the drum assembly. Because the drum assembly has a stronger negative charge it attracts the toner to make it “stick” the image onto the drum.
After the toner is coated onto the drum the corona wire will give a sheet of paper negative charge to pull the toner off the drum. The drum and the paper move at the same speed letting the paper pick up the image exactly as it was created on the drum. In color laser printers, the developing process is repeated four times, once for each color (cyan, magenta, yellow, black).
With inkjet printers, the liquid printer ink is absorbed into the paper once it hits the paper. But toner is a powdery substance so there is nothing holding it to the paper but the electric charge. To apply the image to the paper, the paper passes through the fuser. With the heat and pressure of the fuser, the toner is “melted” into the fibers of the paper.
To prepare for the next page, soft plastic blades wipe off any excess toner left on the drum. The drum passes through the discharge lamp to “erase” any remaining electrical charge on the drum. To begin the process again, the drum is recharged by the corona wire.
Parts of an Laser Printer & How they Work
Photoreceptor Drum and Corona Wire
The core of the laser printer. A metal cylinder, made of a layer of photoconductive material, which holds the raster image created by the laser. A charged wire gives off an electrostatic charge to both the drum and paper.
Fuser and Developer Unit
Heated by internal lamps, paper passes through the two rollers to fuse the toner into the fibers of the paper. A collection of small, negative charged, magnetic beads that are attached to a rotating metal roller. The developer unit moves the magnetic beads through the toner hopper to pick up toner to be deposited onto the drum.
Toner and Toner Hopper
A powdered ink that is given an electrical charge so it can “stick” onto the drum and paper. Since toner is fused to the printed material, it doesn’t bleed or smudge easily as liquid ink.The toner hopper is where the toner is stored. A discharge lamp removes any residual charge left on the drum after a page as been printed.
When the laser is “drawing” the page, instead of moving across the drum it bounces the beam off a movable mirror. As the mirror moves, a light shines through a series of lenses.
Printer Driver and Controller
A printer driver is software that acts as a translator so that the printer can understand data and instructions from your computer. The driver describes the text, image, etc. to be printed and translates it into the printer language.The controller is the “command station” of the printer. The control circuitry is responsible for decoding information sent from the computer, via the printer driver, to the printer, as well as controlling the various parts of the printer.
Are you going to be printing primary black and white documents or are you going to be printing color graphics? Is the printer for personal home use or for a small office?
- Faster than inkjets
- Less maintenance
- More expensive
- Only higher end models print in color
* $200 & Up
Which Laser Printer is Right for Me?
If you are going to use the laser printer for a home office or in a business office, monochrome laser printers offer the best balance between print quality, price and speed.
Personal laser printer prices have dropped down around $200 making them an alternative to inkjet printers. For almost the same price of some of the higher end inkjet printers, some monochrome laser printers are faster and are less expensive to maintain.
If you are going to need a printer to print primarily text as well as the occasional graphic/picture, you might want to consider buying a monochrome laser printer or an inexpensive inkjet printer.
Color Laser Printers
Small businesses needing to print color brochures, photographs, or othe color graphics should look into buying a color laser printer. Color lasers are some of the most expensive printers, but because of their quality and speed, they are a good solution for offices and small businesses.
Personal Laser Printers
Most personal laser printers are monochrome printers. They work best in printing text and simple graphics. You won’t find many personal color printers because of their high prices. However, with several color lasers being priced for less than $1,000, they do make a possible alternative to inkjets.
Workgroup laser printers have the same features as a personal laser but have added features designed for multiple users. These features could include input/output trays, duplex printing, sorting and stapling. Workgroup printers will have faster processors and more memory to be able to handle multiple tasks.
Features to Consider
Print resolution is the maximum number or dots per square inch that can be printed, measured horizontally and vertically. The more dots per inch will give you finer details such as cleaner text and sharper images.
If printing mainly text look for a laser printer with a resolution of 600×600 dots per inch. If you will be printing more than text consider a printer with a resolution of 1200×1200 dots per inch.
Print speed is measured by the number of pages the printer can print out in a minute. The cost of any printer will go up depending on its speed. A personal laser printer should be able to print 15-20 pages per minute.
When it comes to print speed, most manufacturers determine their print speeds using the simplest text in draft mode, so in most cases print speeds are almost twice the speed you will actually have. Print speed will ultimately be determined by the page complexity, the connection speed, and the printer’s memory.
Toner Cartridges & Drum
You can find many printers with separate toner and drum units or with the toner and drum is one disposable part. Having a separate toner cartridge and drum unit will save you money because you will only have to replace the toner cartridge when it runs out. Having the units combined might be easier to replace but you will have to purchase the whole unit when one goes out.
Before you purchase a new printer, check what kind of connections your computer supports. Most printers do not come with a printer cable that connects the printer to the computer so you will need to include this cost when budgeting for a new printer.
Memory will play an important part in the print speed of your printer. The more memory your printer has the faster it will be. Documents that are in queue (or waiting to be printed) are sent to the printer’s memory. If you are printing emails, word documents and the occasional picture, memory is not a very important function. Everyday printing usually doesn’t take as much memory. Look for a printer with more built in memory if you are planning to print large text documents and color graphics.If your printing demands happen to change, there are printers that you can upgrade with more memory.
If the printer is going to be used by multiple users, check to ensure the printer will be network ready. Many personal printers are not made to be set up on a network.