Sunday, December 2, 2012

Printers & Scanners

Setting up wireless or network printers and scanners for mobile devices, home or business.


A printer is a peripheral which produces a representation of an electronic document on physical media such as paper or transparency film. Many printers are local peripherals connected directly to a nearby personal computer. Individual printers are often designed to support both local and network connected users at the same time. Some printers can print documents stored on memory cards or from digital cameras and scanners.

Multifunction Printers - (MFPs) include a scanner and can copy paper documents or send a fax; these are also called multi-function devices (MFD), or all-in-one (AIO) printers. Most MFPs include printing, scanning, and copying among their many features.

Laser Printer - Produces high quality text and graphics. As with digital photocopiers and multifunction printers (MFPs), laser printers employ a xerographic printing process but differ from analog photocopiers in that the image is produced by the direct scanning of a laser beam across the printer's photoreceptor.

LED Printer - Uses an array of LEDs instead of a laser to cause toner adhesion to the print drum.

Liquid Inkjet Printers - Operate by propelling variably sized droplets of liquid ink onto almost any sized page. They are the most common type of computer printer used by consumers.


A Scanner is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop (or flatbed) scanner where the document is placed on a glass window for scanning.

Hand-held Scanners - where the device is moved by hand, have evolved from text scanning "wands" to 3D scanners used for industrial design, reverse engineering, test and measurement, orthotics, gaming and other applications.

Mechanically Driven Scanners - move the document are typically used for large-format documents, where a flatbed design would be impractical.

Direct physical connection to a computer

The amount of data generated by a scanner can be very large: a 600 DPI 23 x 28 cm (9"x11") (slightly larger than A4 paper) uncompressed 24-bit image is about 100 megabytes of data which must be transferred and stored. Recent scanners can generate this volume of data in a matter of seconds, making a fast connection desirable.

Scanners communicate to their host computer using one of the following physical interfaces, listing from slow to fast:

Parallel Port - Connecting through a parallel port is the slowest common transfer method. Early scanners had parallel port connections that could not transfer data faster than 70 kilobytes/second. The primary advantage of the parallel port connection was economic and user skill level: it avoided adding an interface card to the computer.

GPIB - General Purpose Interface Bus. Certain drumscanners like the Howtek D4000 featured both a SCSI and GPIB interface. The latter conforms to the IEEE-488 standard, introduced in the mid ’70's. The GPIB-interface has only been used by a few scanner manufactures, mostly serving the DOS/Windows environment. For Apple Macintosh systems, National Instruments provided a NuBus GPIB interface card.

Small Computer System Interface (SCSI) - supported by most computers only via an additional SCSI interface card. Some SCSI scanners are supplied together with a dedicated SCSI card for a PC, although any SCSI controller can be used. During the evolution of the SCSI standard speeds increased, with backwards compatibility; a SCSI connection can transfer data at the highest speed which both the controller and the device support. SCSI has been largely replaced by USB and Firewire, one or both of which are directly supported by most computers, and which are easier to set up than SCSI.

Universal Serial Bus (USB)  - can transfer data quickly, and they are easier to use and cheaper than SCSI devices. The early USB 1.1 standard could transfer data at only 1.5 megabytes per second (slower than SCSI), but the later USB 2.0 standard can theoretically transfer up to 60 megabytes per second (although everyday rates are much lower), resulting in faster operation.

FireWire  - an interface that is much faster than USB 1.1 and comparable to USB 2.0. FireWire speeds are 25, 50, and 100, 400 and 800 megabits per second (but a device may not support all speeds). Also known as: IEEE-1394.  Proprietary interfaces were used on some early scanners that used a proprietary interface card rather than a standard interface.

Indirect (network) connection to a computer

Some setups allowed a single scanner connected to a host computer to function as a scanner accessible by all users within a local computer network.  All-in-one multi-purpose devices targeted to serve both (small) offices and consumers usually combine a printer, scanner, copier and fax into a single apparatus available to a whole workgroup, providing each individual fax, scan, copy and print functionality.


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