Using Information Technology

1. Using Information Technology Chapter 5 Hardware: Outside the box

2. Expected outcome after this lecture After this lecture, students are expected to be able to: • Give examples on different types of Input and Output devices • Understand how mechanical and optical mouse works • Discuss the advantages and features provided by different types of scanners (handheld v.s. flatbed) • Explain how CRT monitor and LCD monitor works and compare their relative advantages • Perform simple calculation on display memory • Explain the different attributes of a monitor (resolution, color depth, dot pitch, refresh rate…) • Compare the mechanism and advantages of different types of printers

3. Input device • Device that translate human readable data into data which can be understand and process by computer • 3 types: • Keyboard type devices – converts characters into computer readable form • Pointing devices – control the position of cursor or pointer on the screen • Source data-entry devices – converts other form of data into computer readable form

4. How to get input from keyboard? • When a key is pressed, the scan code is generated and the character will be stored in buffer for further process. • Information is sent to PC via PS/2 or USB port • Wireless interface is becoming more common

5. Different types of keyboards 101 Keyboard - Total 101 keys 104 Keyboard (for Win) - With Start Menu/Menu keys Ergonomic Keyboards -Reduce fatigue

6. The future… Virtual Laser Keyboard Senseboard Virtual Keyboard

7. First Mouse - by Doug Engelbart in 1968

8. Mechanical Mouse Use a rubber ball to detect motion Inside the socket, there are 2 rollers arranged at 90o A Roller moves a wheel with holes The wheel block/unblock the light of Infrared LED emitter/receiver, hence enable the detection of speed

9. Optical Mouse • No ball / wheel • Work on almost all surfaces • LED at the bottom emits light to surface • Light rebound and is captured by sensor • (Taking 1500 pictures per second) • Pictures are sent to Digital Signal Processor (DSP) to detect the motion

10. Multi-touch • Multi-touch technology is becoming more and more common nowadays • Apart from specifying position(s) as in typical pointing devices and touch-screen, multi-touch supports “Gestures” which is mapped to operations like zoom, reload, flip page…etc

11. In the News: Microsoft-Surface • Computer from MS, supporting multi-touch gesture, multi-user interaction and object recognition. • Possibilities: • Project/Games with multi-users • Information counters (e.g. showing maps, menus..etc) • Art / Entertainment (draw picture with a “real” brush?) • Interaction with other hand-held devices…etc. • http://www.youtube.com/watch?v=rP5y7yp06n0

12. Source data-entry devices • No keystroke is required to input data • Data is entered directly from the source and translated into digital format • Bar-code reader • Digital camera • Fax machine • Image scanner • Voice recognition • Biometric scanner (e.g. fingerprint)

13. Biometric scanners

14. Scanner • Handheld scanner • Rely on the user to move • Poor image quality • Flatbed scanner • Light and sensor moved by motorized belt. • Additional Features • Scanning of photographic negatives • Auto Document Feeder • Software: Denoise, OCR (Optical Character Recognition)

15. Output device • Device that translate information processed by computer into human readable form • Two Types: • Hardcopy • In a printed form • Printer, plotter, microfilm, microfiche

16. Output devices • Softcopy • Display on screen, voice output, sound output, video output, mechanical output

17. Display screens • Monitor, Cathode-Ray Tube (CRT) • A vacuum tube (chamber) used as a display screen • The screen of a CRT is filled with Red/Green/Blue phosphor dots / pixels (picture element) • A CRT works by moving an electron beam back and forth across the back of the screen • When the beam pass across the screen, it lights up phosphor dots • Fast response time • Images are clear and bright • Big, heavy and consume more power

18. LCD – liquid crystal display • Light shine through a layer of crystalline liquid to make an image • Relatively Thinner and lighter • Low power consumption (only 1/3 of CRT) • Images might not be clearly viewed from an angle • Usually has longer response time and yields “motion blur”

19. How fine your display can be? • Screen size (diagonal length measured in inch) • Resolution • A measure of the number of pixels used for the whole screen • Determines the fineness of display details • 640480, 800600, 1024768, etc. • Color depth • Number of possible colors for each pixel • 256 color (8 bits), High color (16 bits), True color (24 bits)

20. Calculation on the number of pixels • For 1280x1024 display, total number of pixels= 1280x1024 = 1310720 pixels = 1.3 Mega pixels • Assume the display uses True Color (24 bits) • Each pixel consumes: 24bits = 24/8 = 3 bytes • Total display memory = 1310720 x 3 = 4MB memory

21. Dot pitch • Amount of space between the centers of adjacent pixels • Smaller space  closer pixels finer image • Refresh rate • Number of times per second that the screen get refreshed • Pixels are recharged to remains bright • Higher refresh rate  More solid image • 60 Hz (1 second refresh 60 times)

22. The future… • 3D LCD monitor by Toshiba

23. Printers • Impact printer / Dot-matrix printer • Direct physical contact between printing mechanism and paper • Similar to a mechanical typewriter • 9 (low quality), 18 or 24 pins (best quality) • Noisy and slow • Still used nowadays to create “carbon copy” in Multi-Layered forms.

24. Non-impact printer • Without direct physical contact • Faster and quieter than impact printer • Ink-jet printers • Print head contains nozzles that are used to spray drops of ink • Heat (Bubble Jet by Canon, HP) vs Vibration (Epson) • 4 (common) or 6 colors • 4 colors – CMYK: Cyan, Magenta, Yellow, Black • 6 colors – CcMmYK: Cyan, cyan, Magenta, magenta, Yellow, Black

25. Four primary colors for printing - CMYK

26. Laser printer • Better quality and more expensive • Fire a laser beam on paper? • An electrostatic process (static electricity) • Black color or 4 colors (CMYK) • Fast printing speed (up to 35 ppm) • May be slower for color (8 ppm)

27. Printing with laser printer

28. Printer qualities • Color • Resolution • The sharpness of text and images on paper • Measured in dots per inch (dpi) • Dot Matrix = 72-144, Ink Jet = 300-2400, Laser = 600-2400 • Speed • Measured in characters per second (cps) or pages per minute (ppm) • Memory • A buffer holding the information waiting to be printed • More memory faster printing (8-32MB, up to 416MB)

29. Comparison on color laser v.s. ink jet • Problems of color ink jet: • Need high quality paper to prevent ink from feathering • Picture is less precise than color laser • Slow (high quality printing in ink jet may takes 10 mins) • Need to wait for a freshly printed page to dry • Ink-jet cartridges are more expensive than laser toner (Although the printer itself is cheaper)

30. All-in-one Printer/Scanner/Fax • Nowadays, some printer firms (e.g. Hewlett-Packard) manufactures various models of all-in-one machines, which combines the functions of scanner, printer and modem • Scanner + Printer = Photo-copier • Scanner + Modem = Fax transmitter • Modem + Printer = Fax receiver

31. Readings • “Using Information Technology”, Ch 6 • http://computer.howstuffworks.com • http://computer.howstuffworks.com/mouse2.htm • http://www.viewsonic.com/monitoruniversity/lcd.htm