Information Technology Output Devices Lecture 6 Presented by Miss N. Nembhard

Output Devices Receives an electrical signal and produces data or information. The purpose of an output device is to translate data and information from electrical impulses (digital) to human readable format.

The Monitor An output device which is necessary for the computer to display an output to the user. The video display Adapter (video card) on the motherboard allows information to leave the processor and appear on the monitor.

Types of Printers 1.Liquid Crystal Display (LCD) These monitors are much thinner and lighter than the bulkier CRT monitors. They also use a lot less energy. LCD monitors use to be very expensive but the prices have fallen drastically. 2. Cathode Ray Tube (CRT) These are bulky monitors that look like old fashioned TVs. They are usually much cheaper than LCDs.

Terms Associated with the Monitor Soft copy - copy of a file shown on the screen. It is intangible. Pixel (Picture Element) - A single point (a dot) in an electronic image. The greater the number of pixels, the better the quality of the image.

Screen Clarity Screen clarity depends on three things: Resolution - Defines the clarity of an image and is specified as the number of dots per inch (dpi). Normally measured by the number of pixels that can be displayed. Dot Pitch - Amount of space between pixels Refresh Rate - Number of times per seconds that the pixels are recharged so that their glow remains bright.

The Printer An output device that produces tangible copies or hard copies. Hard copy -A tangible copy of a document produced by the printer e.g. flyer, letter, book, a card etc.

Categories of Printers There are two main categories of printers: Impact - the printing mechanism makes physical contact with the paper Non-Impact - No physical contact between the printing mechanism and the paper.

Types of Impact Printers There are two main types of impact printers: Line Printers Character printers Both types of impact printers print on perforated paper.

Line Printers Printers that can use multiple print hammers to print an entire line of text at one time (or at least fast enough so that it appears so). Disadvantages: It cannot print graphics The text it prints is of low quality

Character (Serial) Printers Character or serial printers are printers that print a character at a time. These are slower than line printers

Types of Character Printers The two main types of character printers are: Daisy wheel Dot matrix printers

Daisy wheel Daisy wheel printers – uses a wheel containing characters that rotates until the right character is facing the paper. Although it prints high quality text, it cannot print graphics. Printing different types of font is also impractical since the wheel have to be changed in order to get a different font.

Dot Matrix Printer The dot matrix printer have a head capable of firing tiny pins arranged in a matrix. As the print head moves back and forth, these pins strike the ribbon causing dots to be made on the paper. These same dots can be used to print text as well as graphics Some dot matrix printer can also print in color.

Dot Matrix Printers They are used to print bills or forms that require carbon copies Print special reports that require large continuous sheets some payroll and accounting sheets

Advantages of Impact Printers Produces carbon copies of information being printed. Inexpensive Maintenance is inexpensive Uses ink ribbons which are inexpensive

Disadvantages of Impact Printers They are relatively slow Draft quality is low Ink ribbons have short lives Noisy

Non Impact Printers Non-Impact printers are printers that print using methods that do not involve striking the paper or an ink ribbon. They are generally faster than most impact printers and quieter. Some types are much more expensive than impact printers Non-Impact printers do not use perforated paper

Types of Impact Printers Inkjet printer Laser printer Thermal printer

Inkjet Printer They squirt very small drops of ink on the paper in order to produce text and images. They are commonly used in the home. The are relatively cheap and produce high quality output at relatively high speed.

Laser Printer A very fast printer that utilizes a laser beam along with a toner and a photoconductive rotating drum in order to produce very high quality output. They are faster than inkjet printers They are called page printers because it appears that they print an entire page at one time. They are usually limited to office use because they are expensive.

Thermal Printers They print by using heat. Some thermal printers use special heat-sensitive paper. Heat is applied to the paper to form text and graphics They have low maintenance cost since there is not the need to buy toner or print ribbon. Some fax machines print using this method.

Advantages of Non-impact Printers Produce high quality and high speed output Almost noiseless uses toner or ink cartridges, which are longer lasting

Disadvantages of Non-Impact Printers Printers are usually expensive Maintenance is also expensive Toner is relatively expensive

Types of Printers Dot Matrix: Impact printer Inkjet: Non-Impact printer Laser: Non-Impact printer

Plotter Output device used to produce high quality drawings (images) and large hard copies e.g. posters. Chosen over printers when high quality graphics and making large clear posters.

Plotters continued Have built in microprocessors that converts characters and instructions into a series of coordinates, which the plotter then plots. Produces high resolution images Used by engineers, graphic designers, architects.

Speakers Sound cards code audio signals into signals which can be used by the speaker, which in turn amplifies them. Sub woofers - Speaker system that can be attached to your PC and speakers to enhance your sound effects.

Computer Output on Microfilm Computer output on film rather than on paper. Stores images on plastic films. Images are held in a much reduced format.

Microfilm Reels of films used to store data or images. Primarily used to store for preserving journals and news papers and hold hundreds of prints on one film.

Microfiche Flat individual sheets of film. Primarily used to preserve government document and college catalogues. A special reader is needed to view the pages stored.

Multimedia Projector Works with a variety of media, e.g. computer, camera, printer and the scanner. It projects and magnifies images on a large white screen normally mounted on a wall some distance from the computer.

Other Types of Output Devices Audio output devices for example: Speakers Head-phones Earphones

Human Readable vs Machine Readable Human Readable - output devices that produce hard or soft copies of information or data that can be read and interpreted by humans Machine readable - devices that output in a form only a computer can process.

Activity Explain the following terms associated with the monitor: Resolution Pixel Dot Pitch Refresh Rate Identify the two main types of printers Give an example of each of the two types of printers you identified above. Differentiate between the terms : “hardcopy” and “softcopy”.

References Information Technology for CSEC, Kelvin Skeete & Kyle Skeete