Downloaded 158 times
Uploaded byরেদওয়ান হৃদয়
Chapter 4 Peter Norton
This document discusses computer output devices and technologies. It describes how monitors have evolved from being uncommon in the 1960s to being integral to the modern computing experience. It outlines the key components of monitors like the cathode ray tube and liquid crystal display, and how video cards impact display quality. The document also covers sound systems and ergonomic considerations for reducing eye strain and electromagnetic field exposure when working with monitors.
More Related Content
Chapter 4 Peter Norton
- 1. • Today, everycomputer features some kind of visual display, but display screens were uncommon until the 1960s. • Modern display and sound systems make the computing experience a more inviting one. Because of these sophisticated output technologies computers are easier to use, data is easier to manage and information is easier to access. • These technologies enable us to play games and watch movies, experiences multimedia events and the PC as a communications tool.
- 2. 4A-2 Monitors • Most commonoutput device • Hardly a moment goes by when you are not looking at your monitor. People often form opinion by looking at the monitor. • Two important hardware devices determine the quality of the image - The monitor itself and video controller.
- 3. • In general,two types of monitors are used with PCs. The first is the typical monitor that comes with most desktop computers, it looks a lot like television screen and works in much the same way
- 4. • Connects tothe video card • Categorized by color output – Monochrome • One color with black background – Grayscale • Varying degrees of gray – Color • Display 4 to 16 million colors
- 5. Monitors • Cathode RayTube (CRT) – Most common type of monitor – Electrons fired from the back – Electrons excite phosphor to glow – Phosphor is arranged in dots called pixels – Dot mask ensures proper pixel is lit – opaque
- 6. Monitors • CRT color –Phosphor dots arranged in triads – Red, green, and blue dots – Three colors blend to make colors – Varying the intensity creates new colors
- 7. Monitors • CRT drawbacks –Very large – Very heavy – Use a lot of electricity
- 8. Monitors • Liquid CrystalDisplay (LCD) – Commonly found on laptops – Desktop versions exist – Solve the problems of CRT – Fluorescent lights provide illumination
- 9. Monitors • Passive matrixLCD – Pixels arranged in a grid – Pixels are activated indirectly • Row and column are activated – Animation can be blurry
- 10. Monitors • Active matrixLCD – Each pixel is activated directly – Pixels have 4 transistors • One each for red, green, blue • One for opaqueness – Transistors arranged in a thin film – Animation is crisp and clean
- 11. Monitors • Drawbacks toLCD – More expensive than CRT – Must sit directly in front of screen – Can be more fragile than CRT
- 12. Monitors • Paper-white displays –High contrast between fore and background • Electro-luminescent displays (ELD) – Similar to LCD – Uses phosphor to produce light • Plasma monitor – Gas is excited to produce light
- 13. Monitors and VideoCards • Monitors impacts user effectiveness • Monitors should have – Crisp text – Clear graphics – Adjustable controls – Clear edges
- 14. Monitors and VideoCards • Size of monitor – Measured in inches – Measured diagonally – Actual size • Distance from corner to corner – Viewable size • Useable portion of the screen
- 15. Monitors and VideoCards • Resolution – Number of pixels on the screen – Higher number creates sharper images – Higher number creates smaller images
- 16. Monitors and VideoCards • Refresh rate • A monitor’s refresh rate is the number of times per second that the electron guns scan every pixel on the screen. – Number of time the screen is redrawn – Modern equipment sets this automatically – Improper settings can cause eyestrain – Important because phosphor dots fade quickly after the electron gun charges them with electrons. – If the screen is not refreshed often enough it appears to flicker, and flicker is one of the main reason causes of eyestrain.
- 17. Monitors and VideoCards • Dot pitch – Critical specification of a colored monitor. – Distance between the same color dots – Ranges between .15 mm and .40 mm – Smaller creates a finer picture and more detailed images will appear on the monitor. – Dot pitch no greater than .28 mm if monitor size is 15 inch. – For larger monitor, Should be less than .22 or equal.
- 18. Video Cards • Thequality of images that a monitor can display is defined by the video card/video controller/video adapter. • Device between the CPU and monitor • Better cards result in better output • Removes burden of drawing from CPU • Have their own processor and RAM • Modern cards have up to 512 MB RAM • Capable of rendering 3D images
- 19. • Video controllersfeature their own built-in microprocessors which frees the CPU from the burden of making the millions of calculations required for displaying graphics. • The speed of the video controller’s chip determines the speed at which the monitor can be refreshed. • VRAM is dual ported ,it can send a screen full of data to the monitor and at the same time receive the next screen full of data from CPU.
- 20. Ergonomics and Monitors •Eyestrain – Fatigue of the eyes – Steps to avoid • Choose a good monitor • Place the monitor 2 – 3 feet away • Center of screen below eye level • Avoid reflected light
- 21. Ergonomics and Monitors •Electronic magnetic fields (EMF) – Generated by all electronic devices – It created during the generation, transmission, and use of low frequency electrical power. – These fields exist near power lines, electrical appliances and any piece of equipment that has an electronic motor. – EMF may be detrimental to health – Steps to avoid • Keep the computer at arms length • Take frequent breaks • Use an LCD monitor
- 22. Data Projectors • Replacedoverhead and slide projectors • Project image onto wall or screen • LCD projectors – Most common type of projector – Small LCD screen – Very bright light – Require a darkened room
- 23. Data Projectors • DigitalLight Projectors/video projectors. – A series of mirrors control the display – May be used in a lighted room
- 24. Sound Systems • Integralpart of the computer experience • Capable of recording and playback
- 25. Sound Systems • Soundcard – Device between the CPU and speakers – Converts digital sounds to analog – Can be connected to several devices – Modern cards support Dolby Surround Sound
- 26. • Dolby® surroundsound expands on stereo to deliver sound from the sides, behind, and even above you—creating a natural, multidimensional sonic environment based on the science of how humans hear. • Dolby Atmos® is the latest development in realistic cinema sound. It provides full creative freedom for filmmakers and ensures that you'll hear the soundtracks exactly as their creators intended.
- 27. Sound Systems • Headphonesand headsets – Replacement for speakers and microphones – Offer privacy – Does not annoy other people – Outside noise is not a factor – Headsets have speakers and a microphone
Editor's Notes
- #7 Teaching tip Unless your students have spend a lot of time with HTML or graphics colors, they will have a hard time grasping how RGB values work. The best methods are to show them various colors and then let them experiment. The website www.lynda.com/hue.html provides decimal-value examples of RGB values. Once the students have seen different colors, open MS Paint and let the students develop their own colors. Challenge them to build pink, orange, brown and any of their favorite colors
- #12 Insider information The limited viewing angle can be an advantage. For high security systems, low viewing angles stop casual glances at the screen.
- #15 Teaching tip It is helpful to draw the relationship between viewable and actual size.
- #16 Insider information Many CRT’s are capable of supporting several resolutions. LCD monitors in contrast often can only support one or two resolutions. The reason are the transistors on the LCD cannot move, while the electron gun on the CRT can simply aim for a smaller pixel. If you are in a computer class, stop and have students adjust their resolution on the screen. The simplest method is to right click the desktop and select properties. Click the settings tab, and adjust the slider. As the students are experimenting, have a student answer why larger resolution numbers make smaller images. The answer is higher resolutions draw with smaller pixels.
- #17 Insider information Whenever a TV camera films a computer monitor, the monitor seems to have a line moving up the screen. This is the monitor refreshing the pixels. The camera films faster than the eye can see, which is why the refresh is noticeable.
- #19 Insider information The two leading video card families are ATI’s Radeon and NVIDIA’s GeForce line. Both offer exceptional graphics cards ranging from $50 to $600.
- #22 Teaching tip Point out to the students that no conclusive study exists that directly list EMF as a cause of cancer, reduced muscle tone or reduced brain function. For more information see http://www.hhs.gov/ and search for EMF.
- #24 Insider information A projector is rated in lumens. This is a measure of how bright the projector is. Higher lumens ratings result in a brighter projector. For a guide to lumens ratings, see http://www.projectorpeople.com/tutorials/lumen-guide.asp.
- #26 Insider Information Sound Blaster is the primary manufacturer of sound cards. Exceptional models start at around $30.00.
- #28 Insider information The PS2 game SOCOM II Navy Seals includes a USB headset to allow verbal communication with other team members.