|
There are two main printing technologies available today - Inkjet and Laser.
Dot Matrix printers were popular in the past and although they are still available, they are now obsolete for home and most business users.
If you intend to use your printer mainly to print colour documents and digital photographs, a colour inkjet printer is probably your best option. Inkjets are relatively cheap to buy, but their "consumables" (i.e. ink and paper) are expensive.
For printing text documents, laser printers produce better quality output than inkjets. Until recently, monochrome laser printers were the only practical option because colour laser printers were too expensive for everyday use. Although colour lasers are getting cheaper, their running costs are still greater than colour inkjets.
Inkjet printers work by spraying ionized ink at a sheet of paper. Magnetized plates in the ink's path direct it onto the paper. Inkjets are capable of producing high quality print approaching that produced by laser printers. A standard inkjet produces a resolution of 300 dots per inch, and more expensive models offer higher resolutions.
Inkjets are generally much cheaper to buy than laser printers, particularly for colour printing. However, they are also considerably slower in operation and more expensive to maintain. Ink cartridges need to be changed more frequently and the special coated paper required to produce high-quality output is expensive. In a cost-per-page comparison, inkjets work out about ten times more expensive than laser printers for high quality output.
Spending between £80-£300 will get you a better quality inkjet printer known as a "photo printer" specially tailored to digital photography. Photo printers offer better resolutions and allow you to print your photographs by plugging your camera's memory card directly into your printer or by connecting your camera via a Universal Serial Bus (USB) cable (make sure your printer has the right interface for your memory card). Photo inkjet printers usually have 6 or more inks and a LCD preview screen gives you more control over your images. Consumables are costly and replacement cartridge costs and paper can soon outstrip the printer's original price. If the cartridge incorporates the print-head, as with most HP & Lexmark printers, you get a printer that is as good as new when you replace the cartridge. If your printer uses a combined colour cartridge, then when one colour runs out you throw away some unused ink.
Running costs for photo printers are high because photographs use up to three times the ink used for regular colour documents. Be aware that the printing speeds quoted by manufacturers are not a good guide to real performance because different standards are used by each company. Computer magazines often run their own performance tests on printers and their independent views are worth consideration.
Laser printers work by producing an image on a small rotating organic photoconductive (OPC) drum. The laser changes the electrical charge on the drum wherever it makes contact. The drum is then rolled through a reservoir of toner, which is picked up by the charged portions of the drum. The toner is transferred to the paper through a combination of heat and pressure.
The main advantage of laser printers is their resolution, i.e. the number of dots per inch (dpi) they can print. Available resolutions range from 300 dpi at the low end to 1,200 dpi at the high end, with 600 dpi resolution now becoming standard for text printout. Compared to inkjets, laser printers produce much better quality black text documents, and they are capable of producing more pages at a much lower cost per page. They are also better at handling envelopes, card and other non-regular media. This makes a monochrome laser printer a good choice for businesses where colour printing is not a requirement. Prices for entry-level monochrome lasers begin at around £60.
Colour laser printers use four toners to print in full colour. Their cost has come down considerably, and entry level colour lasers can now be found for between £100-£200. For photo printing, however, colour lasers cannot compete with a good inkjet using glossy photo paper.
During the lifetime of the printer, the OPC drum needs to be periodically replaced as its surface wears out and print quality deteriorates. Toner cartridges also run out and need to be replaced. Usually the toner cartridge and the OPC drum are housed separately, but in some printers, the drum is located inside the cartridge so that when the toner runs out, the drum must also be replaced, which greatly adds to the running costs of the printer and is very wasteful.
Colour laser printers can have up to nine separate consumables items - four colour toners, an OPC drum, a developer unit, a fuser unit, fuser oil and a waste toner bottle. The high component count is a major factor when considering the purchase of a colour laser printer.
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. This allows you to to add more fonts to the basic set of internal or resident fonts that are supplied with the printer and also allows more complex pages to be printed. To print a full-page graphic at 300 dpi, you need at least 1 MB (megabyte) of printer RAM. For a 600-dpi graphic, you need at least 4 MB RAM.
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).
Dot matrix printers work by striking pins against an ink ribbon to print closely spaced dots into the appropriate shape. Along with daisywheel printers, dot matrix printers have been superseded by non-impact printers. Their major advantage over laser and inkjet printers is the ability to print carbon copies of a page in a single pass. Compared to inkjets, they are expensive to buy, but the running costs are a lot lower. However, they cannot produce the high-quality output of lasers or inkjets, cannot print in colour and are also very noisy in operation.
The speed of a dot matrix printer is given in characters per second (cps). This can vary from about 50 to over 500 cps. Most models offer different speeds depending on the quality of print required.
Print quality is determined by the number of pins in the printing head that print the dots. This varies from 9 to 24 pins. The best dot matrix printers (24 pins) produce near letter-quality type.
Flatbed scanners are now the most common type of scanner. They are the best and most versatile choice for capturing photo prints and documents, and good quality models can now be bought for well under £100. Sheet-feeder scanners with page rollers are still found in low-end multi-function (fax) units.
Hand-held scanners are obsolete.
A flatbed scanner is similar to a copy machine in that it has a glass plate under a lid, and a moving light that scans across under it.
It can scan photos, paper documents, books, magazines, even 3-dimensional objects that don't have a lot of depth. Unlike a copier, however, the scanner creates a digital image rather than a paper copy.
Transparencies must be back-lit to be scanned so a transparency adapter will be required. This is included with some scanners, but with others it is an optional extra. Most adapters will also accept framed slides, but it's best to check before you buy if you plan to use this facility. 35mm film must be scanned at very high resolution to produce a good-sized image, so a dedicated film scanner (that can also automatically cope with dust and scratches) is better for this purpose.
Optical Resolution
For standard scanning of photographs and other documents, a resolution of 300 ppi (pixels per inch) is usually all you need. Larger resolutions will result in huge images and file sizes. For scanning negatives or if you plan to print enlargements of your photographs, however, look for at least 2,400ppi.
Colour Depth
The greater the colour depth (or bit-depth), the better the scanner will be at differentiating different shades of each colour. 24-bit colour depth is the minimum required for decent colour scans. This gives a colour depth of 8bits for red, green and blue, or 256 shades of each colour. In theory, this means that a 24-bit scanner can detect a total of 1.6 million colours. However, if you plan to use your scanner to scan slides or negatives, a colour depth of 36bit or 48bit is preferable.
Scanning Area
Look for a scanning area at least 8.5 x 11.7 inches, allowing A4 size documents to be scanned. Scanners up to A3 size are available, but the table space ("footprint") required may become a consideration.
Software
A scanner is operated through software, so look for bundled software packages. Most image-editor programs allow you to scan an image. Also look for an included OCR (optical character recognition) package if you plan to scan editable text documents.
Document management utilities are also useful. Make sure the scanner provides drivers suitable for your computer's operating system version.
A multi-function peripheral combines a printer and scanner into a single unit and also provides copying and fax facilities. This can represent a significant saving over buying these devices separately, and also needs less desk space. Basic models can cost well under £100, for which you can expect an inkjet printer capable of printing at 2400x1200 dpi and a scanner with resolution of 600x1200 dpi. (As always with inkjet printers, running costs are likely to be high).
The cheapest mono laser multi-function printers begin at around £150, which gives improved print speed and lower running costs. Both sheet-feed and flatbed scanning facilities may also be available. The cost of a colour laser multi-function unit currently begins at around £300.
UKorbit Computers page
Visit UKOrbit's Consumer & Advice Centre for further help and information.
|
