Laser printer

Laser printer:

A computer peripheral which produces high quality output to paper allowing us to view the data away from the computer.

[Hewlett-Packard Laserjet 6l]

Use

Used for Computer printouts such as;

Letters (word processing)
customer statements (accounting)
House plans (CAD - often a plotter used)
Brochures, fliers, small publications (Desktop publishing )

Features

A non-impact dot matrix printer using a process similar to that of a photocopy machine to form a page image on a drum

Print a page at a time.
Quiet in operation
Toner cartridges used to store ink.
Generally cut sheet A4 and smaller

Example printers

HP Laserjet Series, IBM 4019 Laser Printer

High Quality. Individual characters are formed like dot matrix characters but the dots are so close together the print looks like a shaped character.
For graphics, number of dots per inch may be selectable (75 dpi = grainy to 600dpi high quality, to 1200dpi for publishing quality).

Print a page at a time.An image of a whole page of print is represented as a series of minute dots, rather like a newpaper picture only better. Require a page definition language to compose the page. The two most common are; Postscript and HP-PCL (Hewlett Packard-Page Composition Language.
both low speed and high speed varieties. A typical high speed Laser printer can print 146 pages per minute! When printing characters this can be expressed as 10,500 lines per minute if the characters are spaced at a normal 6 lines per inch vertically but 21,000 lines per minute if characters are spaced at 12 lines per inch vertically. Heavy duty printers are appearing and replacing many line printers. Eg Production of Telephone accounts.

Operation

prlaser.gif (3604 bytes)

Paper is fed into the laser printer from an input tray
Paper is given a static charge
Rotating mirror reflects laser that projects the image of the page onto a rotating drum
Toner is transferred to the statically charged paper.
Toner is bonded to the paper using a hot roller.

Classification

Print method

Page Printers
which print whole pages at a time.

Non-impact printers.

Use an electrostatic method to form an image on the paper.

Speed.

Lasers are typically rated as pages per minute.
Vary from medium speed (PC based) to high speed (attached to mid-range and mainframe computers).

When working with a printer there are many skills you need to be "printer competent". Once a printer has been correctly connected, and the proper drivers installed for your software, you will need basic skills to operate it.
These include;

Changing Paper
Setting/changing form length
Changing an ink (toner) cartridge
Changing Mode

For your printer these are outlined in the manual that should have been supplied with your printer.

Changing Paper

Cut Sheet
Ensure 'correct side' printed on (photocopy paper has a right side and wrong side for printing) This will improve print quality

Setting/changing form length

On a laser generally set in the software.

Changing an ink cartridge.

Toner Cartridge
Once toner has run out cartridges are usually thrown out (may be refilled though many manufacturers do not recommend or guarantee their printers!

Changing Mode.

Quality
Draft mode -Set by reducing the dots per inch (dpi) to 75 or 150. For inbuilt text fonts makes no difference to the text quality. High speed/fewer dots printed giving a lighter "grainer" graphics. Greatly reduces the memory requirements.
Letter (High) Quality - slow speed with the maximum number of dots printable. For office lasers 600dpi though 1200dpi laser starting to appear.

Font
Type of print eg. Times Roman, Courier, Helvitica

Controls

Most Printers Contain a Front panel of switches to manage their features; some important ones include;

online
* On Allows the printer to communicate with the PC
* Off Allows you to set printer characteristics via the front panel.

form feed
* For continuous stationery will feed the paper the 'pre-set' number of lines (often 66), from a 'pre-set 'top of form'
* For Cut sheet, this will eject the current page and set up the next page for printing.

Note
As a Laser printer is 'page' based "line feed" has no meaning.

Diagnosis

Exercise

List steps you should take if your printer does not print. You should refer to the manual supplied with the printer you use.
Troubleshooting