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webpointmorpheus Computer Info
Printers
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Overview
Types of Printers
Print Languages
Print Modes
Laser Printing
©2005 - material compiled by Bob Carnaghi, www.webpointmorpheus.com
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- Overview Top of Page
- Printers and the print technology certainly make up a class of hardware in itself. In an office environment where printers are networked, a large percentage of tech support can/will be dedicated to printer maintenance and troubleshooting. In the broad sense, there are three basic types of printers. Each type has its own particular architecture, which supports the specific purpose of the printer.
Types of Printers
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| Printer |
Description |
| Impact |
Daisy Wheel or Dot Matrix (9 or 24 pins) |
| Inkjet |
Spray ink on paper |
| Laser |
Write with a laser. Also called Electrographic Printer (EP) |
- Printer Languages Top of Page
- When an item is sent to a printer to be printed, it must be converted into a format that is understood by the printer. In the formats listed below, ASCII treats the printed item as text. The PCL is proprietary, and will not tolerate sharing across different format types. Postscript is the most common, and treats the print job as an image.
Printer Languages
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| Language |
Description |
| ASCII |
A standard set of commands with limited printer control functions |
| PCL (HP Printer Control Lanaguage) |
HP's own hardware dependent printer language |
| Postscript (PDL) Page Description Language) |
A hardware independent language capable of high resolution graphics |
- Print Modes Top of Page
- Print mode is the method of sending or transmitting the print job down the wire.
Parallel Print Modes
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| Mode |
Description |
| Compatability |
Unidirectional, obsolete |
| Nibble |
Limited Bi-directional, (4-bits) obsolete |
| Byte (SPP) |
Bi-directional, most common |
| EPP(Enhanced Parallel Port) |
Fast Bi-directional, eliminates CPU from transfer process |
| ECP(Extended Capability Port) |
Fastest, (faster than EPP), Bi-directional, allows compression and DMA. |
- Laser Printing Top of Page
- Laser printing is 'the Big Kahuna' of printing. It produces a faithful, indellible image on the print medium. Laser printers tend to be expensive and complex. Listed below is an outline of the laser printing process.
Laser Printing Process
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| Process |
Definition of Process |
- Cleaning
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A photosensitive drum's surface is cleaned and prepared to hold an image. A rubber cleaning blade removes excess toner from the drum. Erase lamps illuminate the drum's photosensitive material and neutralizes any charges that remain from previous print jobs. |
- Conditioning
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The cleaned drum is now conditioned with a uniform negative charge on the photosensitive drum by the use of the primary corona wire. The high-voltage power supply applies a high negative charge to the primary corona wire. Negative charges from the wire migrate to the surface of the drum. The system uses a primary corona grid which sits between the primary corona and the drum's surface to regulate the (-600V to -1600V) negative voltage that is applied. |
- Writing
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To the cleaned and contitioned drum a sweeping laser beam now writes the image to the drum by means of a positive electrical charge applied to the uniformly negatively charged drum. |
- Developing
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Toner is applied to the drum by applying a negative charge (-200V to -500V.) The areas of the drum that were written to by the laser are positive, and attract the negatively charged toner. The areas of the drum that were not written to by the laser remained negatively charged, and now repel the toner. |
- Transfer
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The image that is on the drum is transferred to paper by the use of a corona wire placed behind the paper which has a positive charge. |
- Fusing
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Before fusing, the toner is very loosely held on the paper by gravity and a small electrical charge. The fusing roller produces a permanent image on the paper by forcing the toner into the paper by pressure and heat. The fusing roller is heated by a high intensity lamp inside the fusing roller. |
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This page was last modified: Wednesday July 20, 2005 7:35 AM |
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