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Text A Output Devices: Printers Technical details A printer is a device that prints your texts or graphics on paper. The output on paper or acetate sheets is called printout or hard copy. A program in your computer, called the printer driver, con- verts data into a form that your printer can understand. A print spooler stores files to be printed when the printer is ready. It lets you change the order of documents in the queue and cancel specific print jobs. The output quality or resolution, is measured in dpi or dots per inch. The speed of your printer is measured in pages per mi- nute (ppm). In a network users can share a printer connected to a print server, a computer that stores the files waiting to be printed. Types of printers Printing is the final stage in creating a document. Since the re- sults you can obtain with different types of printer will vary sub- 67
stantially, here is a guide to help you decide which one is most suitable for your needs. To begin with, you should take into account that printers vary in cost, speed, print quality, and other factors such as noise or printing method. Technology is evolving so quickly that there is always a printer for every application or need.
shape a character. A print head containing tiny pins strikes an inked ribbon to make letters and graphics. This impact printing technology allows shops, for example, to print multi-part forms such as receipts and invoices, so it’s useful when self-copying pa- per and continuous-form labels are needed. It has two important disadvantages: noise and a relatively low resolution (from 72 to 180 dpi). They are slower than laser printers but much cheaper. Inkjet printers generate image by spraying tiny, precise drops of ionized ink directed by magnetic plates onto the paper. The res- olution ranges from 300 to 1,200 dpi, suitable for small quantities or home use. An inkjet printer consists of a print head, ink cartridges, paper feed assembly, belt and stabilizer bar. Inkjet printers are capable of creating high-quality images and high-resolution photos with vivid colours. They can work with most types of papers. Inkjet printers have many advantages. Compared to most printers, they are affordable, easy to use and inherently quiet. They are ready to print and do not require any warm-up time. They are also compact, generally requiring less space. With these features, they are more popular as home or business printers. There are certain disadvantages for inkjet printers. The print head is less durable in most cases. Inkjet printer ink is expensive and can potentially dry up, causing not only wastage of ink but al- so blockages within the printer. Also, compared to laser printers, they are slow to work and thus are not considered suitable for high-volume printing.
resolution of l,200–2,400 dpi. They scan the image with a laser 68
beam and a special powder called toner is attracted to paper by an electrostatic charge and then fused on by a hot roller. They are constantly being improved. In terms of speed and image quality, laser printers are preferred by experts for various reasons, for in- stance, they have a wider range of scalable fonts than inkjets, can emulate different language systems, and can produce high-quality graphics. Lasers use a page description language or PDL which describes how to print the text and draw the images on the page. The best- known languages are Adobe PostScript and HP Printer Control Language. жүктеу/скачать 1,47 Mb. Достарыңызбен бөлісу:
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