input and output devices
- 1. 1 Table of Contents Input devices.............................................................................................................................. 2 Key boards......................................................................................................................................3 Mouse............................................................................................................................................4 Mechanical Mouse .................................................................................................................................................................4 Laser Mouse ............................................................................................................................................................................4 Optical Mouse.........................................................................................................................................................................5 Blue Track Mouse:..................................................................................................................................................................5 Joysticks.........................................................................................................................................5 Pointing-stick..................................................................................................................................6 Track ball .......................................................................................................................................6 Touch pad ......................................................................................................................................7 Game controller..............................................................................................................................8 Touch screen ..................................................................................................................................8 Output devices........................................................................................................................... 9 Monitor........................................................................................................................................10 CRT (cathode ray tube) monitors: .....................................................................................................................................10 LCD (Liquid Crystal Display) monitors:..............................................................................................................................11 LED (Light-Emitting Diodes) monitors: .............................................................................................................................12 Speakers.......................................................................................................................................13 Head phones.................................................................................................................................13 Data projector..............................................................................................................................14 Printer..........................................................................................................................................15 Impact printers:.........................................................................................................................16 Non-impact printer:...................................................................................................................18 Plotters ........................................................................................................................................20
- 2. 2 Input and Output devices Input devices In computing, an input device is a peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or other information appliance. Examples of input devices include keyboards, mouse, touch -pad, track ball, pointing stick, game controllers and joysticks.
- 3. 3 Key boards A keyboard is a typewriter-style device, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches. Keyboards are the main input device for computers. A keyboard typically has characters engraved or printed on the keys and each press of a key typically corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce letters, numbers or signs (characters), other keys or simultaneous key presses can produce actions or execute computer commands. Keyboard is the most commonly used device for direct (human) input of alphanumeric data into computers. In normal usage, the keyboard is used as a text entry interface to type text and numbers into a word processor, text editor or other programs. In a modern computer, the interpretation of key presses is generally left to the software. A computer keyboard distinguishes each physical key from every other and reports all key presses to the controlling software. Keyboards are also used for computer gaming, either with regular keyboards or by using keyboards with special gaming features, which can expedite frequently used keystroke combinations. A keyboard is also used to give commands to the operating system of a computer, such as Windows' Control-Alt-Delete combination, which brings up a task window or shuts down the machine. A command-line interface is a type of user interface operated entirely through a keyboard, or another device doing the job of one.
- 4. 4 Mouse A mouse is a pointing device that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, which allows for fine control of a graphical user interface. Physically, a mouse consists of an object held in one's hand, with one or more buttons. Mice often also feature other elements, such as touch surfaces and "wheels", which enable additional control and dimensional input. Various types of mouse are available in market and the selection solely depends on your requirement. Let’s take a quick look at the available options: Mechanical Mouse: Also called as the ball mouse, a mechanical mouse has rubber or metal ball on its underside. When the ball rolls, mechanical sensors inside the mouse detect the direction and move the pointer on the screen of the PC. This type of mouse requires a flat surface or a mouse pad to work efficiently. One of the drawbacks of the device is that it is more prone to attracting dust. Optical-mechanical Mouse: An optical-mechanical mouse is same as the mechanical mouse except that the sensors used in it are optical and not mechanical. The device is a combination of optical and mechanical technologies, wherein, the ball is present but the mouse movement is detected optically leading to more accuracy. Laser Mouse: A laser mouse is the new generation mouse with two necessary components – light emitter and light detector. A laser mouse uses laser as the light emitter and has a precise scanning of mouse movement. You will find a laser mouse ranging anywhere between 1000- 5700 dots-per-inch (DPI).
- 5. 5 OpticalMouse: An optical mouse also has light emitter and light detector but it uses LED as the light emitter. It generally has lower DPI than laser mouse and users might find difficulty in using the device on black or shiny surfaces. Blue Track Mouse: The next generation mouse from Microsoft, it is based on the Blue Track Technology that enables the mouse to track efficiently on any surface, be it a granite countertop or a carpet. The blue beam in mouse is a combination of image sensor and pixel geometry & is four times larger than the average laser beam used in laser mouse. It generates high-contrast pictures of the surface for an exceptional tracking accuracy. Joysticks A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. A joystick, also known as the control column, is the principal control device in the cockpit of many civilian and military aircraft, either as a center stick or side-stick. Joysticks are often used to control video games, and usually have one or more push-buttons whose state can also be read by the computer. A popular variation of the joystick used on modern video game consoles is the analog stick.
- 6. 6 Pointing-stick A pointing stick is an isometric joystick used as a pointing device, as with a touchpad or trackball, and typically mounted in a computer keyboard. Movements of the pointing stick are echoed on the screen by movements of the pointer (or cursor) and other visual changes. The pointing stick operates by sensing applied force, by using a pair of resistive strain gauges. A pointing stick can be used by pushing with the fingers in the general direction the user wants the cursor to move. The velocity of the pointer depends on the applied force so increasing pressure causes faster movement. The relation between pressure and cursor or pointer speed can be adjusted, similar to the way the mouse speed is adjusted in a traditional desktop computer. Track ball A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a pointer. Compared with a mouse, a trackball has no limits on effective travel; at times, a mouse can reach an edge of its working area while the operator still wishes to move the screen pointer farther. With a trackball, the operator just continues rolling, whereas a mouse would have to be lifted and re-positioned. Some trackballs have notably low friction, as well as being made of dense material such as glass, so they can be spun to make them coast. The trackball's buttons may be situated to that of a mouse or to a unique style that suits the user.
- 7. 7 Touch pad A touchpad is a pointing device featuring a tactile sensor, a specialized surface that can translate the motion and position of a user's fingers to a relative position on the operating system that is outputted to the screen. Touchpads are a common feature of laptop computers, and are also used as a substitute for a mouse where desk space is scarce. Because they vary in size, they can also be found on personal digital assistants (PDAs) and some portable media players. Wireless touchpads such as Apple's Magic Trackpad are also available as detached accessories.
- 8. 8 Game controller A game controller is a device used with games or entertainment systems to provide input to a video game, typically to control an object or character in the game. A controller is usually connected to a game console or computer by means of a wire or cord, although, since the mid- 2000s, wireless controllers have become widespread. Input devices that have been classified as game controllers include keyboards, mice, gamepads, joysticks, etc. Special purpose devices, such as steering wheels for driving games and light guns for shooting games, are also game controllers. Touch screen A touchscreen is an input device normally layered on the top of an electronic visual display of an information processing system. A user can give input or control the information processing system through simple or multi-touch gestures by touching the screen with a special stylus/pen and-or one or more fingers. Some touchscreens use ordinary or specially coated gloves to work while others use a special stylus/pen only. The user can use the touchscreen to react to what is displayed and to control how it is displayed (for example by zoom the text size).
- 9. 9 Output devices An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) which converts the electronically generated information into human-readable form. Examples of output devices include monitors, printers, plotters, speakers, head phones and data projectors.
- 10. 10 Monitor Monitor is a standard output devices. This shows the output information. Monitor is also one of the important parts of computer, because without monitor, system can't work. So, that this is the standard output device. At present, computer monitors are available in a variety of shapes, designs, and colors. However, based on the technology used to make computer monitors, they can be broadly categorized into three types. 1. CRT (Cathode Ray Tube) 2. LCD (Liquid Crystal Display) 3. LED (Light-Emitting Diodes) CRT (cathode ray tube) monitors: These monitors employ the CRT technology used most commonly in the manufacturing of television screens. In this, a stream of intense high energy electrons is used to form images on a fluorescent screen. A cathode ray tube is a basically a vacuum tube containing an electron gun at one end and a fluorescent screen at another end. From this electron gun, a process called thermionic emission generates a strong beam of electrons. These electrons travel through a narrow path within the tube with high speed using various electro-magnetic devices and finally strike the phosphor points present on the fluorescent screen, thus creating an image. There are several advantages of using CRT monitors: •CRT monitors are affordable and cost effective. •Unlike conventional CRT monitors, modern technological advancements have resulted in the development of flat screen CRT monitors that reduce the glare and are good for the eyes. However, the only concern with buying CRT monitors is that they are heavy and can occupy a great deal of work space. Also, these devices get heated up very easily.
- 11. 11 LCD (Liquid CrystalDisplay)monitors: Liquid crystal display, also known as liquid crystal diode, is one of the most advanced technologies available at present. It is a flat-panel display. Typically, an LCD monitor consists of a layer of color or monochrome pixels arranged schematically between a couple of transparent electrodes and two polarizing5/16/2015 filters. Optical effect is achieved by polarizing the light in varied amounts and making it pass through the liquid crystal layer. Some major advantages of using an LCD monitor include: These monitors are compact, lightweight, and do not consume much desk space. Secondly, these monitors do not consume much electricity and can even be operated by using batteries. Also, the images transmitted by these monitors do not get geometrically distorted and have little flicker. However, LCD monitors do have certain disadvantages. Most importantly, these monitors are very expensive. Secondly, image quality is not constant when viewed from different angles. Also, an LCD monitor’s resolution is always constant. Any alterations can result in a reduced performance.
- 12. 12 LED (Light-Emitting Diodes) monitors: LED monitors are the latest types of monitors in the market today. Like LCD, it is again a flat panel display making use of light-emitting diodes for back-lightning instead of Cold Cathode Fluorescent (CCFL) back-lightning used in LCDs. Primarily, the display is of LCD only but the back-lightning is done by LEDs. LED monitors are said to use much lesser power than CRT and LCD. Thus, they are also considered environmental friendly. Other core advantages of LED monitors are: They produce images with higher contrast They have less negative environmental impact when disposed Because of the technology, the monitor panels can be made very thin Do not produce much heat while running
- 13. 13 Speakers Computer speakers, or multimedia speakers, are speakers external to a computer that disable the lower fidelity built-in speaker. They often have a low-power internal amplifier. Computer speakers range widely in quality and in price. The computer speakers typically packaged with computer systems are small, plastic, and have mediocre sound quality. Some computer speakers have equalization features such as bass and treble controls. Head phones Headphones are a pair of small loudspeakers that are designed to be held in place close to a user's ears. They are electroacoustic transducers which convert an electrical signal to a corresponding sound in the user's ear. Headphones are designed to allow a single user to listen to an audio source privately, in contrast to a loudspeaker which emits sound into the open air, allowing anyone nearby to listen. They are also known as ear speakers, earphones. In the context of telecommunication, a headset is a combination of headphone and microphone.
- 14. 14 Data projector A data projector is an image projector that receives a video signal and projects the corresponding image on a projection screen using a lens system. All data projectors use a very bright light to project the image, and most modern ones can correct any curves, blurriness, and other inconsistencies through manual settings. Video projectors are widely used for many applications such as, conference room presentations, classroom training, home theatre and concerts. Projectors are widely used in many schools and other educational settings, sometimes connected to an interactive whiteboard to interactively teach pupils.
- 15. 15 Printer “A printer is an external output device that takes data from a computer and generates output in the form of graphics / text on a paper”. A printer is an electromechanical device which converts the text and graphical documents from electronic form to the physical form. Generally they are the external peripheral devices which are connected with the computers or laptops through a cable or wirelessly to receive input data and print them on the papers. A wide range of printers are available with a variety of features ranging from printing black and white text documents to high quality colored graphic images.
- 16. 16 There are two types of printers. 1. Impact printers 2. Non-impact printers Impact printers: An impact printer is a type of printer that operates by striking a metal or plastic head against an ink ribbon. The ink ribbon is pressed against the paper, marking the page with the appropriate character, dot, line, or symbol. The three most common forms of impact printers are dot-matrix, daisy-wheel, and line printers. Dot-MatrixPrinters: The technology behind dot-matrix printing is quite simple. The paper is pressed against a drum (a rubber-coated cylinder) and is intermittently pulled forward as printing progresses. The electromagnetically-driven print head moves across the paper and strikes the printer ribbon situated between the paper and print head pin. The impact of the print head against the printer ribbon imprints ink dots on the paper which form human-readable characters. Dot-matrix printers vary in print resolution and overall quality with either 9 or 24-pin print heads. The more pins per inch, the higher the print resolution. Most dot-matrix printers have a maximum resolution of around 240 dpi (dots per inch). While this resolution is not as high as those possible in laser or inkjet printers, there is one distinct advantage to dot-matrix (or any form of impact) printing. Because the print head must strike the surface of the paper with enough force to transfer ink from a ribbon onto the page, it is ideal for environments that must produce carbon copies through the use of special multi-part documents. These documents have carbon (or other pressure-sensitive material) on the underside and create a mark on the sheet underneath when pressure is applied. Retailers and small businesses often use carbon copies as receipts or bills of sale.
- 17. 17 Daisy-Wheel Printers: If you have ever worked with a manual typewriter before, then you understand the technological concept behind daisy-wheel printers. These printers have print heads composed of metallic or plastic wheels cut into petals. Each petal has the form of a letter (in capital and lower-case), number, or punctuation mark on it. When the petal is struck against the printer ribbon, the resulting shape forces ink onto the paper. Daisy-wheel printers are loud and slow. They cannot print graphics, and cannot change fonts unless the print wheel is physically replaced. With the advent of laser printers, daisy-wheel printers are generally not used in modern computing environments. Line Printers: Another type of impact printer somewhat similar to the daisy-wheel is the line printer. However, instead of a print wheel, line printers have a mechanism that allows multiple characters to be simultaneously printed on the same line. The mechanism may use a large spinning print drum or a looped print chain. As the drum or chain is rotated over the paper's surface, electromechanical hammers behind the paper push the paper (along with a ribbon) onto the surface of the drum or chain, marking the paper with the shape of the character on the drum or chain.
- 18. 18 Non-impact printer: A non-impact printer prints characters and graphics on a piece of paper without striking the paper. Some of these printers use spray ink while others use heat and pressure to create images. These printers are faster than impact printer. Non-impact printers do not use a striking device to produce characters on the paper; and because these printers do not hammer against the paper they are much quieter. Two types of nonimpact printers often used with microcomputers are laser printers and ink-jet printers. Laser printer: Laser stands for light amplification by stimulated emission of radiation. The laser printer is a non-impact printer. Its working is similar to photocopying machine. It uses laser beams to burn special powder on page to create a permanent image. The power is contained in toner. Laser printer prints complete page at a time. It is also known as page printer. The printing speed of laser printers is 5 to 300 pages per minute (ppm). The speed depends on the contents being printed. The plain text is printed faster than graphics. Laser printer prints text and graphics in a high quality resolution, a typical laser printer provides the resolution of 1200dpi or more. Laser printer prints at higher speed than inkjet and dot matrix printers. It does not make much noise. Laser printer is mostly used in business field.
- 19. 19 Ink-jet printer: An ink-jet printer is a type of non-impact printer. It prints characters and graphics by spraying tiny drops of liquid ink on paper. These printers can produce quality text and graphics in both black-and-white and color including photos. A typical inkjet printer provides resolution of 300 dots per inch. The latest inkjet printers provide higher resolution. The price of inkjet printers is less than laser printers. However, they are slower than laser printers. Most inkjet printers can print from 10 to 35 pages per minute. However, they print graphics and colors at slower rate. The print quality of inkjet printers is higher than dot matrix printer. They are also comparatively inexpensive. Most inkjet printers usually have two print cartridges. One cartridge contains black ink and the other contains color.
- 20. 20 Difference between impact and non-impact printers Impact printer / Dot-matrix Printer Non-impact Printer / Laser Printer 1. It prints characters or images by striking print hammer or wheel against an inked ribbon. 1. It prints characters and images without striking the papers. 2. Its speedis slower. 2. Its speedis faster. 3. Its printing quality is lower. 3. Its printing quality is higher. 4. It normally uses continuous paper sheet. 4. Its normally uses individual paper sheet. 5. It generates noise during printing. 5. It does not generate noise during printing. 6. It uses inked ribbon for printing. 6. It uses toner or cartridge for painting. 7. It is less expensive. 7. It is more expensive. 8. Dot matrix is an impact printer. 8. Laser printer is a non-impact printer Plotters A plotter is an output device that is used to produce high quality graphics in a variety of colors. Plotters are used to create maps, architectural drawings, graphs and charts. Types of Plotters Different types of plotters are as follows: 1. Flatbed plotter 2. Drum Plotter
- 21. 21 Flatbed plotter: Flatbed plotter is used to plot of draw images. It contains pens for drawing images. The paper is places on table-like surface. Software instructs the pens to move down on the paper. The pen then moves on the paper for creating images. Most flatbed plotters have one or move pens of different colors and widths. Drum plotter: Drum plotter uses a rotating drum or cylinder. The drawing pens are mounted on the drum. The pens move to the left and right as the drum rotates. This movement creates the desired image. The advantage of drum plotter is that the length of the plot is almost unlimited. The roll paper can be used to draw very lengthy images. The width of the image depends on the width of the drum.