Introduction To Computers PDF

Introduction to Computers Dr.Eng. Mahmoud Abu_Alfutuh Chapter 3 Input and Output Devices lesson 4 Output Devices This lesson includes the following sections: Monitors Sound Systems Printers  Output Devices Output devices are used to outputting of the information...

Introduction to Computers Dr.Eng. Mahmoud Abu_Alfutuh Chapter 3 Input and Output Devices lesson 4 Output Devices This lesson includes the following sections: Monitors Sound Systems Printers  Output Devices Output devices are used to outputting of the information that has been processed from the computers. Output device translates data into human- understandable language. The output is presented in the form of visuals, sound or a hard copy (printed on paper).  Output Devices Output devices include monitors, projectors, printers, and speakers. 1-Monitors Categories of Monitors CRT (Cathode Ray Tube) Monitors Flat-Panel Monitors Comparing Monitors Video Controllers  Monitors The monitor is the most used output device on personal computer. Monitor is also known as a Visual Display Unit (VDU). The major function of a monitor is to display processed data like images, videos, text, etc.  Monitors - Categories of Monitors Monitors are categorized by the technology they use: Cathode ray tube (CRT) monitors Flat-panel displays  Monitors - CRT Monitors In CRT monitors, electrons are fired at phosphor dots on the screen. The dots are grouped into pixels, which glow when struck by electrons. In color CRTs, each pixel contains a red, green, and blue dot. These glow at varying intensities to produce color images.  Monitors - CRT Monitors CRT monitors provide a bright, clear picture at a relatively low cost. There are two major disadvantages, however, associated with CRT monitors: 1- Because CRT monitors are big, they take up desktop space and can be difficult to move. 2- CRT monitors require a lot of power to run.  Monitors - Flat-Panel Monitors Flat-panel monitors have been used primarily on portable computers. A new generation of large, high-resolution, flat-panel displays is used with desktop computers. These new monitors take up less desk space, require a lot of power to run, and run cooler than traditional CRT monitors.  Monitors - Flat-Panel Monitors Most flat-panel monitors use liquid crystal display (LCD) technology. Passive matrix LCD uses a transistor for each row and column of pixels: less expensive, narrow viewing angle, they don’t “refresh” the pixels very quickly. Active-matrix LCD uses a transistor for each pixel on the screen: expensive, wider viewing angle, faster refresh. Flat-panel monitors take up less desk space; less radiation  Monitors - Comparing Monitors When comparing monitors, consider four features: Size Resolution Refresh rate Dot pitch  Comparing Monitors - Size A monitor's size is the diagonal measurement of its face, in inches. For years, 15" monitors (13"viewing area) were standard. Today, 17" monitors (15" viewing area) are common. Larger monitors are available but can be expensive.  The diagonal size (often 15”) Comparing Monitors - Resolution Resolution is the number of pixels on the screen, expressed as a matrix (such as 600x800). A 17" monitor offers resolutions from 640x480 up to 1280x1024. The Video Graphics Array (VGA) standard is 640x480. Super VGA (SVGA) monitors provide resolutions of 800x600, 1024x768 or higher. Comparing Monitors - Resolution Five commonly used resolution settings: (a) 640 X 480, (b) 800 x 600, (c) 1024 X 768, (d) 1152 X 864, and (e) 1280 X 1024. Note that, as the resolution increases, the image on the screen gets smaller. Comparing Monitors - Refresh Rate Refresh rate is the number of times each second that the electron guns scan the screen's pixels. Refresh rate is measured in Hertz (Hz), or cycles per second. Look for a refresh rate of 72 Hz or higher. A slower rate may cause eyestrain. Fast scanning = Quick refresh (less flicker)  Comparing Monitors - Dot Pitch Dot pitch is the distance between the phosphor dots that make up a single pixel. In color monitors, three dots (red, green, and blue) comprise each pixel. Look for a dot pitch no greater than.28 millimeter. Fine dot pitch = Crisp displays  B+G R+B R+G R+B+G Phosphor Dot Color Mixing R: Red, G: Green, B: Blue  Monitors - Video Cards The video card (controller) is an interface between the monitor and the CPU (Central Processing Unit). The video controller determines many aspects of a monitor's performance, such as resolution or the number of colors displayed. The video controller contains its own on-board processor and memory, called video RAM  Video Control Board with Monitor Cable VRAM Graphic intensive applications such as games require plenty of VRAM.  PC Projectors A PC projector connects to a PC and is used to project images on a large screen. Many PC projectors provide the same resolutions and color levels as high-quality monitors. Projected Screen  Sound Systems Multimedia PCs come with a microphone, sound card, and speakers. A sound card translates digital signals into analog ones that drive the speakers. The speakers transfer a changing electric current to sound. With the right software, you can use your PC to edit sounds and create special sound effects.  Sound Systems: Sound Cards A computer's sound card converts sound from analog to digital form, and vice versa for recording or playback. A sound card has both input and output functions  Sound Systems: speakers The speakers transfer a constantly changing electric current to a magnet, which pushes the speaker cone back and forth. The moving speaker cone creates pressure vibrations in the air—in other words, sound. Sound Systems:Headphones and Headsets Headphones include a pair of speakers, which are plugged into the output jack of a computer's sound card. A headset includes one or two speakers and a microphone. Headsets replace both remote microphones and speakers  Overview of Printers Categorizing Printers Evaluating Printers  Overview of Printers - Categorizing Printers Printers fall into two categories: Impact printers, and Non-impact printers. Non-impact printers: Two types of printers have become the most popular: ink jet, and laser. Overview of Printers - Evaluating Printers When evaluating printers, consider four criteria: Image quality – Measured in dots per inch (dpi). Most printers produce 300 – 600 dpi. Speed – Measured in pages per minute (ppm) or characters per second (cps). Initial cost – Cost of operation – This refers to the cost of supplies used by the printer. Ink Jet Printers How Do Ink Jet Printers Work? Performance Ink Jet Printers – How Do Ink Jet Printers Work? Ink jet printers are an example of non-impact printers. The printer sprays tiny droplets of ink onto the paper. Ink jet printers are available for color and black-and-white printing.  Ink Jet Printers - Performance Ink jet printers offer speeds of (2 – 4 pages per minute ppm) and resolution (300 – 600 dots per inch dpi), comparable to low-end laser printers. Ink jet printers are inexpensive and have low operating costs. Laser Printers How Do Laser Printers Work? Performance Laser  Laser Printers – How Do Laser Printers Work? Laser printers are non-impact printers. They use heat and pressure to bond particles of toner to paper. Laser printers are available for color and black-and-white printing.  Laser Printers - Performance Laser printers provide resolutions from 300 – 1200 dpi and higher. Black-and-white laser printers usually produce 24 – 40 ppm. Laser printers produce higher-quality print than ink jet printers but are more expensive.  Plotters A plotter is a device that prints high-quality graphics in a variety of color formats. It works in a similar way to a printer. It is used to print large maps, architectural drawings, and large-format printing.  Inkjet Plotter Plotters use mechanical, ink jet, or thermal technology. Thank you