Computer Output Devices Lecture PDF

Output Devices  Today’s Goal To learn about the Basic Components of Computer To learn about the Computer Hardware and its Function COMPONENTS OF COMPUTER OUTPUT DEVICES  WHAT IS OUTPUT An output is the data that has been processed in t...

Output Devices  Today’s Goal To learn about the Basic Components of Computer To learn about the Computer Hardware and its Function COMPONENTS OF COMPUTER OUTPUT DEVICES  WHAT IS OUTPUT An output is the data that has been processed in that form which is useful for the user or machine for future processing. Output can be in two forms Soft Copy and Hard Copy.  WHAT ARE OUTPUT DEVICES Any hardware component used to show results after processing to any user and to send the results of processing to the user. Output can be text, Audio, Video & graphics. WHAT ARE OUTPUT DEVICES Examples  Monitor  Printer  Plotter  Projectors  Speakers  Headphone etc.  MONITOR/DISPLAY DEVICES “Monitor or display devices are used to get output on screen. It is like small television and available in different sizes and specifications. The text which is displayed on screen is called softcopy.  TYPES OF MONITOR There are majorly two type of monitor according to its specification. These are  Monochrome monitor  Color monitor  MONOCHROME MONITOR Monochrome monitor is based on a single color that can be white, blue, black or gray etc. these type of monitors are same like the old mobile phones which have a single color in back ground with black text in display. Later, this type of output screens were useful in the devices where we needed simple display. Like some ATM machines, mobile phones, specific digital devices like PDA, pagers etc.  COLOR MONITOR Color monitor is such monitor which is based on colors as its name implies. Today mostly monitor are based on color display rather it is flat panel or tube based monitors. The basic colors in those monitors are three which are RGB stands for Red, Blue, Green by these basic colors a monitor can generate many other colors by the combination of these basic colors.  FEATURES & SPECIFICATION When we talk about monitor specification and features then there are several factors which we have to keep in our view. Whenever we want to buy monitor we have to keep these features in our view:  Color  Size  Resolution  Pixel Pitch  Refresh rate  COLOR Monitor can view different colors specifically some monitor can view only single color in its background and black text on its screen these monitors are very simple (as defined above) is called monochrome monitors. Monitor work with three basic colors and by these three colors it makes different colors in by combinations. These colors are RGB, mean Red, Green and Blue. By combinations it can make 256 colors. More colors more exclusive display.  SIZE Like television monitor is also available in different sizes. The size started from15 inches to 22 inches monitor.  RESOLUTION An important characteristic of all monitor screens is its resolution. The screen is divided in to vertical and horizontal lines and intersecting of these lines make many small boxes and these boxes in used to display images, called pixels  RESOLUTION Each point of light on the screen is called a pixel. The resolution of a screen is the number of pixels that the screen can display. This is given as the number of pixels across (horizontal resolution) by the number of pixels down (vertical resolution). For example, 800 x 600. The greater the resolution the better. Modern screens can display 1024 X 768 or better.  PIXEL PITCH The distance between two pixels on screen is called pixel pitch. it is also an important feature of monitor. If we want to view clear images on monitors it must have less distance between pixels. That pixel pitch is also called dot pitch. It is measured in millimeters.  REFRESH RATE The refresh rate is the number of frames per second the television can display. Its unit is a Hertz, which is equal to 1/second. 120Hz means it can draw 120 images per second. Every monitor has a electric gun behind screen. That gun omits light and makes images to the screen. Refresh rate is that time which gun used to regenerate new image on screen. Refresh rate is measured in hertz. It is also an important feature for better quality of display. This is the number of times the image is refreshed every second. A low refresh rate makes the image appear to flicker. You need a refresh rate of at least 72 Hz (72 times a second) to avoid the appearance of flicker  CRT MONITORS The cathode ray tube (CRT) type monitors and Televisions make use of the same technology. A beam of electrons is fired from an electron gun at the back of the tube. This strikes the front of the tube which is covered in a phosphorescent material which glows when struck by electrons. Between the electron gun and the screen the beam is modulated by a signal to produce the image you see on the screen. CRT MONITORS  LCD MONITORS The LCD monitors bring lots of advantages when compared to the CRT ones. The first advantage which is also the most obvious one is the fact that the LCD monitors are smaller and have a smaller weight than the CRT monitors. The LCD monitors can be placed on the table and they use far less space than the CRT monitors. This is a great advantage. The picture quality of the LCD monitors is better as well, which means that the movies will be displayed in a better quality and the display of the games will have better colors, and so on. Uses fluorescent lighting.  LCD MONITORS In most of the cases the LCD monitors will have certain features which provide additional functionality. Some of the LCD [liquid crystal display] monitors have USB [Universal Serial Bus] hubs, HDMI [High Definition Multimedia Interface] input, TV tuners etc. The TV tuner is very important because you can use the computer for watching TV. The aspect ratio of the monitors has changed. The resolution will be highly influenced by the monitor size. The larger the size of the monitor is the larger resolutions it will have. If you buy the biggest monitor that you can buy because the experience of watching movies or playing games on it will be much more enjoyable.  TOUCH SCREEN MONITORS These monitors use touching of the screen as an input method. Items can be selected or moved with a finger, and finger motions may be used to convey commands. The screen will need frequent cleaning due to image degradation from fingerprints.  PRINTERS The second most common form of computer output is printed documents. Although a computer can operate perfectly without a printer, it is certainly helpful to the user to have one. People often prefer to get printouts of the work they have done rather than to look at it on the screen it is considered a form of hard  Types of Printer Printer has majorly two types. Impact printers Non impact printers  IMPACT PRINTERS Impact printers produce output by striking a ribbon with a hammer. When the ribbon is hit a mark is made on the paper behind it. If carbon paper is put into the printer then an impact printer can print more than one copy of a document at a time. This feature is often used by companies when they print invoices, bills etc. Because of the hammering action impact printers are noisy when they are printing. Impact printers are slow and noisy. IMPACT PRINTERS  NON IMPACT PRINTERS Non-impact printers do not produce images by striking against the paper because there is no hammering action. Non-impact printers are very quieter and faster than impact printers. These printers produce high quality output.  INK JET PRINTERS Ink jet printers are the most popular type of printer for use at home or in a small business. This is because they are relatively cheap to purchase and can print in color. Ink jet printers generate output by spraying tiny jets of ink at the paper to be printed on. A column of ink jets in the print head moves across the page spraying dots onto the page to make the image.  INK JET PRINTERS Ink-jet printers can work in black and white or color. Black and white versions cost a little less and color ones cost comparatively higher. They are slower than laser printers and cost slightly more to run. Its resolution is 300 – 720 DPI (Dots per inch)  LASER PRINTERS Laser printers are called Page Printers because they print a whole page at a time. A laser beam is used to draw the image to be printed onto a light sensitive Drum. After the image has been drawn on the drum a fine powder ink called Toner is put onto it. The toner only sticks where the laser has drawn the image. The paper then passes over the drum and the toner is transferred onto the paper.  LASER PRINTERSS Laser printers produce very high quality output, are very quiet and very fast. Typical home laser printers can print 8 pages per minute (ppm). Some industrial versions print over 40ppm and can print on both sides of a piece of paper at the same time. The main disadvantage of this type of printer is the high cost. Running costs are higher than impact printers but lower than most ink jet printers. Its resolution is 600 to 2400 DPI (Dots per Inch)  THERMAL PRINTERS Thermal printers are no longer used as printers for PCs. They are however still used in some computer control systems, cashboxes and in many fax machines. These printers print on special heat sensitive paper which is expensive. The image is produced from small dots using wax based cartridges which are made on the paper by heating it up. The quality is reasonable and graphics can be printed.  PLOTTERS A plotter is a special output device used to produce hard copies of large graphs and designs on paper, such as construction maps, engineering drawings, architectural plans and business charts. The plotter is either a peripheral component that you add to your computer system or a standalone device with its own internal processor. Plotters are generally more expensive than printers, ranging from about 100,000 to $750,000 (or even more). PLOTTERS  SPEAKERS/ HEADPHONE Speakers and headset are used to get audio output. A system's speaker is the component that takes the electronic signal stored on things like CDs, tapes and DVDs and turns it back into actual sound that we can hear. In any sound system, ultimate quality depends on the speakers. The best recording, encoded on the most advanced storage device and played by a top-of-the-line deck and amplifier, will sound awful if the system is hooked up to poor speakers.  MULTIMEDIA/PROJECTORS A Digital Projector/Multimedia is an electro-optical machine which converts image data from a computer or video source to a bright image which is then imaged on a distant wall or screen using a lens system. The cost of a device is not only determined by its resolution, but also by its brightness. The projector serves the following purposes: Visualization of data stored in a computer for presentations Demonstration of program products for a large number of prospective customers The projector replaces the white board as well as written documents. Watching moving images from a video tape player or digital video disk player. Digital projectors may also be built into cabinets which use a rear projection screen to form a single unified display device, now popular for "home theater" applications.