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PRINTERS

Printer - A device that prints text or illustrations on paper. There are many different types of printers. In terms of the technology utilized, printers fall into the following categories:


Dot matrix: A type of impact printer that produces characters and illustrations by striking pins against an ink ribbon to print closely spaced dots in the appropriate shape. Dot-matrix printers are relatively expensive and do not produce high-quality output. However, they can print to multi-page forms (that is, carbon copies), something laser and ink-jet printers cannot do.

Dot Matrix Printer Manufacturers include Epson, Okidata and Brother

Dot-matrix printers vary in 3 important characteristics:


Speed: Given in characters per second (cps), the speed can vary from about 50 to over 500 cps. Most dot-matrix printers offer different speeds depending on the quality of print desired.

Print quality: Determined by the number of pins (the mechanisms that print the dots), it can vary from 9, 18 or 24pins. The best dot-matrix printers (24 pins) can produce near letter-quality type, although you can still see a difference if you look closely.

Ink: Dot Matrix Printer use ribbon for ink

In addition to these characteristics, you should also consider the noise factor. Compared to laser and ink-jet printers, dot-matrix printers are notorious for making a lot of noise.


Ink-jet: A type of printer that works by spraying ionized ink at a sheet of paper. Magnetized plates in the ink's path direct the ink onto the paper in the desired shapes. Ink-jet printers are capable of producing high quality print approaching that produced by laser printers. A typical ink-jet printer provides a resolution of 600 dots per inch, although some newer models offer higher resolutions.


Ink Jet Printer Manufacturers include Canon, Epson, HP and Lexmark


Speed: Given in Pages per Minute (PPM) the higher the PPM the more pages they can print. Most ink-jet printers offer different speeds depending on the quality of print desired.

Print quality: Determined by the DPI Dot Per Inch Example 2440 x 1220 DPI (Vertical and Horizontal DPI) The higher the DPI the better in terms of print quality.

Ink: Ink-Jet Printers use Ink Cartridges (hidden cost)

In general, the price of ink-jet printers is lower than that of laser printers. However, they are also considerably slower. Another drawback of ink-jet printers is that they require a special type of ink that is apt to smudge on inexpensive copier paper.

Because ink-jet printers require smaller mechanical parts than laser printers, they are especially popular as portable printers. In addition, color ink-jet printers provide an inexpensive way to print full-color documents.


Laser: A type of printer that utilizes a laser beam to produce an image on a drum. The light of the laser alters the electrical charge on the drum wherever it hits. The drum is then rolled through a reservoir of toner, which is picked up by the charged portions of the drum. Finally, the toner is transferred to the paper through a combination of heat and pressure. This is also the way copy machines work.


Laser Printer Manufacturers include HP, Lexmark, Xerox


Speed: Given in Pages per Minute (PPM) the higher the PPM the more pages they can print. Most ink-jet printers offer different speeds depending on the quality of print desired.

Print quality: Determined by the DPI Dot Per Inch Example 4880 x 2440 DPI (Vertical and Horizontal DPI)

Ink: Laser Printers use Toner Cartridges

Laser Printer Parts

• Toner Cartridge Components
• EP Photosensitive Drum
• Erase Lamp
• Primary Corona Wire
• Toner
• Transfer Corona
• Fuser
• Power Supplies
• Turning Gears
• Motherboard
• Ozone Filter
• Sensors
• Switches

Because an entire page is transmitted to a drum before the toner is applied, laser printers are sometimes called page printers. There are two other types of page printers that fall under the category of laser printers even though they do not use lasers at all. One uses an array of LEDs to expose the drum, and the other uses LCD's. Once the drum is charged, however, they both operate like a real laser printer.


One of the chief characteristics of laser printers is their resolution -- how many dots per inch (dpi) they lay down. The available resolutions range from 300 dpi at the low end to 1,200 dpi at the high end. By comparison, offset printing usually prints at 1,200 or 2,400 dpi. Some laser printers achieve higher resolutions with special techniques known generally as resolution enhancement.

In addition to the standard monochrome laser printer, which uses a single toner, there also exist color laser printers that use four toners to print in full color. Color laser printers tend to be about five to ten times as expensive as their monochrome siblings.

Laser printers produce very high-quality print and are capable of printing an almost unlimited variety of fonts. Most laser printers come with a basic set of fonts, called internal or resident fonts, but you can add additional fonts in one of two ways:

Font cartridges: Laser printers have slots in which you can insert font cartridges, ROM boards on which fonts have been recorded. The advantage of font cartridges is that they use none of the printer's memory.

Soft fonts: All laser printers come with a certain amount of RAM memory, and you can usually increase the amount of memory by adding memory boards in the printer's expansion slots. You can then copy fonts from a disk to the printer's RAM. This is called downloading fonts. A font that has been downloaded is often referred to as a soft font, to distinguish it from the hard fonts available on font cartridges. The more RAM a printer has, the more fonts that can be downloaded at one time.

In addition to text, laser printers are very adept at printing graphics. However, you need significant amounts of memory in the printer to print high-resolution graphics. To print a full-page graphic at 300 dpi, for example, you need at least 1 MB (megabyte) of printer RAM. For a 600-dpi graphic, you need at least 4 MB RAM.

Because laser printers are no impact printers, they are much quieter than dot matrix. They are also relatively fast, although not as fast as some dot-matrix printers. The speed of laser printers ranges from about 4 to 20 pages of text per minute (ppm). A typical rate of 6 ppm is equivalent to about 40 characters per second (cps).

Laser printers are controlled through page description languages (PDL's). There are two de facto standards for PDL's:

PCL: Hewlett-Packard (HP) was one of the pioneers of laser printers and has developed a Printer Control Language (PCL) to control output. There are several versions of PCL, so a printer may be compatible with one but not another. In addition, many printers that claim compatibility cannot accept HP font cartridges.

PostScript: This is the de facto standard for Apple Macintosh printers and for all desktop publishing systems.

Most software can print using either of this PDL's. PostScript tends to be a bit more expensive, but it has some features that PCL lacks and it is the standard for desktop publishing. Some printers support both PCL and PostScript.


The 6 steps laser printing process

NOTE * easy way to remember this is CLEAN CARS WILL DRIVE TO FAST

1. Cleaning – The Photosensitive drum is cleaned before it can take on a new image

2. Conditioning or Charging – To make the drum receptive to new images, it must be charged. The EP drum is given a negative charge by the primary corona wire around -600 and -1000 volts

3. Writing - A laser beam is use to write to the EP drum causing dots on the drum to lose some of the negative charge
and become relatively positive charge

4. Developing - A toner is transferred from the toner cylinder to the EP drum by attracting the area of the drum that has a
Relative positive charge

5. Transferring - The transfer corona wire puts a highly positive charge on the paper once the paper has a positive charge
the negatively charge toner particle leaps from the drum into the paper

6. Fusing - The compression roller and fusing roller press and melts the toner into the paper the fuser gets very hot

Other Types of Printers

Photo Printer – Is a type of printer use for printing photographs.

photo printer

Dye-Sublimation Printer
– Is a type of printer which employs a printing process that uses heat to transfer dye to a medium such as a plastic card, printer paper or poster paper.

dye sublimation printer

Thermal Printer- Is a type of printer that produces a printed image by selectively heating coated thermo chromic paper, or thermal paper as it is commonly known, when the paper passes over the thermal print head. The coating turns black in the areas where it is heated which then produce an image.

thermal printer

All-in-One Printer - A printer than can also do scanning, fax and make copies

hp printer

Plotter - A large device use to print large posters and documents

plotter printer

Types of Printer Cables

USB – Standard USB Printer Cable speed is around 12Mbps.


Parallel – IEEE 1284 Standard Cable speed is around 1.5 to 2.77Mbps

IEEE 1284 standard supported the following:

Supports 5 modes of operation (Compatibility, Nibble Mode, Byte Mode, EPP and ECP)

Supported a standard physical interface
Supported impedance and termination
Supported a standard method of connecting a host PC and peripheral device

Serial – RS232 Standard Printer Cable speed is around 57Kbps


Printer Connections

Network, or commonly Ethernet, connections are commonplace on network laser printers, though some other types of printers do employ this type of connection. Generally, network printers are designed to be shared using a central file/print server, though you can share them off a workstation in a “workgroup” environment.

RJ45

Parallel is the original standard for printers and a lot of basic printers still rely on the parallel port connection. A parallel (also called LPT port) sends and receives data simultaneously, transmitting data in parallel. Parallel uses a DB25 connection on the computer side and an oddly shaped 36 pin connection on the printer called the centronics port.

Parallel Port Centronics


USB, or Universal Serial Bus, is a very common connector type for personal printers being sold today. USB is sold as the next generation of standard ports for computers. USB allows mice, keyboards, scanners, printers, most peripherals to connect to a computer. It supports up to 12 Mbps transfer rate and is hot swappable.

USB_A USB_B


Infrared is not very commonly used. An Infrared acceptor allows your devices (laptops, PDAs, Cameras, etc) connect to the printer and send print commands via infrared signals.
Serial allows your printer to connect to your computer via the serial port.


Firewire is a high speed connection commonly referred to as IEEE1394, its “standard”. Though not specifically mentioned in the preparation outline for the exam, you should be aware that a printer may connect via Firewire. Firewire is a high speed connection typically used for digital video editing or other high bandwidth requirements.

6pin Firewire port

Wireless connection such as Bluetooth is also popular for connecting printers in a network environment


An HP Jet direct (or Printer Server Box) is a device which allows a non-networkable printer to be networked. For example, we have an Epson color inkjet printer in our office which has a standard parallel port connection on it. The Jet Direct box allows the printer to be connected into our network and allows the printer to be shared off of our file/print server.

 

 



 



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