Seeing Hearing And Printing Data

Seeing Hearing and Printing Data

What is a printer? • A printer is an output device that produces text and graphics on paper.

Major types of printer • impact printer (Dot Matrix) – Impact printer produces text and images when tiny wire pins on print head strike the ink ribbon by physically contacting the paper • Non-impact printer (Laser / Inkjet/ Thermal) – Non-impact printer produces text and graphics on paper without actually striking the paper.

Categories of printers • • • • Dot-matrix printers Inkjet printers Laser printers Thermal printers

Printers and their uses • Inkjet printers and laser printers are the most popular printer types for home and business use. • Dot matrix printer was popular in 70’s and 80’s but has been gradually replaced by inkjet printers for home use. • Dot matrix printers are still being used to print multi-part forms and carbon copies for some businesses.

Dot-matrix printers • Dot-matrix printer is an impact printer • It produces text and graphics when tiny wire pins on the print head strike the ink ribbon. • The print head runs back and forth on the paper like a typewriter. • When the ink ribbon presses on the paper, it creates dots that form text and images. • Higher number of pins means that the printer prints more dots per character, thus resulting in higher print quality.

Dot-matrix printers [Cont.] • • • Dot matrix printers have a horizontally moving head with a vertical line of pins mounted inside. An inked ribbon is located between the head and the paper and as the head moves the pins strike the ribbon to form each character as a series of dots. The best quality printers have heads with 24 pins and low quality ones have 9 pins (although by making two passes and shifting the head half a pin pitch between them they can effectively act as as a 18 pin head). As these printers can produce small dots anywhere on the paper most support graphics and have software fonts. Dot matrix printers are quite noisy but can be cheap. They are mostly for low to medium quality, low volume personal use. They are obsolete now. • • • •

Advantages of dot matrix printer 1) 2) 3) 4) Can print on multi-part forms or carbon copies Low printing cost per page Can be used on continuous form paper, useful for data logging Reliable, durable

Disadvantages of dot matrix printer 1) 2) 3) 4) Noisy Limited print quality Low printing speed Limited color printing

Inkjet printers • • Inkjet printers are non-impact printers which print text and images by spraying tiny droplets of liquid ink onto paper. The inkjet head design is also divided into two main groups: – Fixed-head • Fixed-head is built into the printer and should last for the whole life of the printer. • It produces more accurate output than cheap disposable head. • The ink cartridges for fixed head printers are also cheaper as the print head does not need to be replaced. • If the head is damaged, the entire printer has to be replaced. – Disposable head. • Disposable head is included in replacement ink cartridge. • It is replaced each time an ink cartridge runs out of ink. • This increases the cost of ink cartridges and also limits the use of high quality print head in these cartridges. • A damaged print head is not a problem as one can easily replace it with a new ink cartridge.

Ink Jet [Cont.] • Ink jet printers have a movable head that can spray fine drops of ink directly on to the paper. • Some have multiple heads carrying coloured inks with the best ones providing a wide range of colours. • As the paper and the head never come into contact they are very quiet. • However they are also rather slow. • They are generally cheaper than laser printers and are suitable for all types of high quality low volume work.

Advantages of inkjet printers 1) 2) 3) 4) 5) 6) 7) Low cost High quality of output, capable of printing fine and smooth details Capable of printing in vivid color, good for printing pictures Easy to use Reasonably fast Quieter than dot matrix printer No warm up time

Disadvantages of inkjet printers 1) Print head is less durable, prone to clogging and damage 2) Expensive replacement ink cartridges 3) Not good for high volume printing 4) Printing speed is not as fast as laser printers 5) Ink bleeding, ink carried sideways causing blurred effects on some papers 6) Aqueous ink is sensitive to water, even a small drop of water can cause blurring 7) Cannot use highlighter marker on inkjet printouts

Laser printers • • • Laser printers are non-impact printers which can print text and images in high speed and high quality resolution, ranging from 600 to 1200 dpi. laser printer use toner (black or colored powder) instead of liquid inks. A laser printer consists of these major components: – – – – drum cartridge, rotating mirror, toner cartridge Roller • • • • • The drum cartridge rotates as the paper is fed through. The mirror deflects laser beam across the surface of the drum. Laser beam creates charge that causes the toner to stick to the drum. As the drum rotates and presses on paper, toner is transferred from the drum to paper, creating images. Rollers then use heat and pressure to fuse toner to paper. Colored laser printers add colored toner in three additional passes.

Laser Printers [Cont.] • In a laser printer, paper is given an electro-static charge by passing it over a charged drum and then a laser scans it discharging all clear areas. • Next the paper is passed over a tray of powdered ink (toner) which is attracted to the charged areas. • Finally the ink is bonded to the paper by heat or pressure. • Laser printers are quiet and are used for high quality low or high volume work.

Advantages of laser printers 1) 2) 3) 4) 5) 6) High resolution High print speed No smearing Low cost per page (compared to inkjet printers) Printout is not sensitive to water Good for high volume printing

Disadvantages of laser printers 1) 2) More expensive than inkjet printers Except for high end machines, laser printers are less capable of printing vivid colors and high quality images such as photos. The cost of toner replacement and drum replacement is high Bulkier than inkjet printers Warm up time needed 3) 4) 5)

Thermal Printers • The use of thermal printers is limited to ATM, cash registers and point-of-sales terminals. • Some label printers and portable printers also use thermal printing. • Thermal printers use two types of printing technologies: – Direct thermal – Thermal transfer

Direct thermal • Traditional thermal printers use direct thermal method by pushing electrically heated pins against heat-sensitive paper (thermal paper). • The coating on the thermal paper turns black in the areas where it is heated, producing characters or images. • Direct thermal printers have no ink, toner or ribbon. • These printers are durable, easy to use and cost less to print than other printers

Thermal transfer • In thermal transfer printing, a thermal print head applies heat to a heatsensitive ribbon, • Ribbon melts ink onto paper and a wide range of materials to form text and images. • The printouts can be extremely durable and can be stored over long period of time.

Specialty Printers • Some printers are named because they are designed for specific functions, such as – Photo printers, – Portable printers – All-in-one / Multifunction printers. • Photo printers and portable printers usually use inkjet print method • Multifunction printers may use inkjet or laser print method

Photo printer • Photo printers are color printers that produce photo lab quality pictures on photo paper. • They can also be used to print documents. • These printers have a very high number of nozzles and can print very fine droplets for improved image quality. • Some photo printers also have media card readers. They can print 4” x 6” photos directly from the media card of digital cameras without a computer in between.

Portable printer • Portable printers are small, lightweight inkjet or thermal printers that allow computer users to print from laptop computers when traveling. • They are easy to carry, convenient to use but generally more expensive than normal inkjet printers due to the compact design. • Their printing speed is also lower than normal printers. • Some portable printers are designed to print photos immediately from digital cameras and are known as portable photo printers.

Multi Function / All-in-One Printers • Multifunction printer (MFP) is also known as all-in-one printer or multifunction device (MFD). • It is a machine that includes several functionalities including printer, scanner, copier and fax. • Multifunction printer is very popular in SoHo (small office / home office) offices. • It can use either inkjet or laser print method. • Some multifunction printers also have media card readers, allowing printing of pictures directly from digital cameras without using a computer.

Advantages / Disadvantages of Multi Function • Advantages of multifunction printers: – Low cost – it is often cheaper to buy a multifunction printer than individual components (fax machine, scanner, printer, copier) separately – Take up less room • Disadvantages of multifunction printers: – If one component is broken, the entire machine has to be replaced – Failure in any component will affect other functions – The print quality and speed may be lower than some stand alone components

Daisy Wheel • On a daisy-wheel printer the complete set of characters is held on a removable wheel which consists of a central collar radiating out from which are a set of spokes, each ending in a single character. • The wheel spins round to align the required character with a single hammer. • The hammer and wheel assembly move across the paper striking it through an inked ribbon. • These printers can produce high quality output but are limited to the range of characters on the wheel. • Changing wheels is simple, this provides alternative fonts, but is no substitute if a wide range of fonts is required. • They are quiet noisy and are used for low volume office work. They are obsolete now.

Line Printer • Line printers have a spinning horizontal drum that stretches the full width of the paper which is separated from it by an inked ribbon. • The drum is made up of 132 thin cylinders each having a complete set of characters. • Behind the paper is a row of 132 hammers that strike the paper at the right moment to select the required character from the corresponding cylinder. • In this way it is able to print a complete line at a time. • Line printers are used for high volume low quality output and are very noisy. They are obsolete now.

Band Printer • A band printer features a rotating band embossed with alphanumeric characters. • Machine rotates the band to the desired character then a small hammer taps the band pressing a character against a ribon. • These are very fast speed printers. • Generated 2000 lines of text per minute.

Plotter • Used to print large format images such as construction drawing, maps • Early plotters were mechanical devices that used robotic arms, which drew the images . – Table Plotters (Flatbed plotters, Used two arms) – Roller Plotters (Drum Plotters, used one arm)