Hardware Devices Input methods and devices Mouse Keyboard Bar code reader Scanners

1. Hardware Devices • Input methods and devices • Mouse • Keyboard • Bar code reader • Scanners • Flatbed Scanner • Fingerprint scanner • Retina Scanner • Iris Scanner • Optical Mark Reader (OMR) • Optical Character Reader (OCR) • Magnetic Stripe reader • Smart Card Reader • RFID Reader • Touch Sensitive Screen • Graphics Tablet • Voice recognition • Digital Still Camera

2. Hardware Devices • Mouse • Designed in 1964 by Douglas Engelbart • Use as a tool to aid use of Graphical user interfaces. • Uses a X-Y positioning system • Latest mouse uses wireless technology and more buttons for different functions.

3. Hardware Devices • Keyboard • Enter text and numbers into a computer • Electronic circuits continually scan the keys to detect key presses • Converted to ASCII code or UNICODE for the computer to understand • Each key press sent as an interrupt to the CPU • Braille Keyboards are used for disabled people.

4. Hardware Devices • Bar code reader • Electronic Device for reading barcodes on various items • A sequence of black and white bars with coded information identifying the product. • Uses the change in light source to read the information. • Converted to ASCII by the scanner for a computer to understand.

5. Hardware Devices • Scanner - Flatbed • Glass plane illuminated from beneath by a bright light • An array of light detecting sensors spanning the width of the glass pane is moved slowly up to pick up any light reflected from the course above. • Converted into an equivalent electric signal. • Colours scanner have three arrays – Red, Green, Blue • A digitised imaged is stored by the computer.

6. Hardware Devices • Scanner - Fingerprint • A security device that takes a picture of your finger. • Sensor and decoder circuitry analyses the captured image and converts it into electric form for processing by a computer against stored fingerprint data. • Some are optical devices using light sensors – others use electrical currents to scan the finger. • Used on PCS to authenticate users.

7. Hardware Devices • Scanner - Retina • Low energy infrared light source that is directed onto the retina • Photoelectric detectors convert the reflected light into an electrical signal to be processed by the computer. • Like the fingerprint the retina is unique for each person.

8. Hardware Devices • Optical Mark Reader • Detects marks placed in predefined positions on a form • Passed under a light source • Intensity of reflected light from each row in the form is measured and converted by photoelectric sensors into an electrical equivalent.

9. Hardware Devices • Optical Character reader • Uses an optical scanner • Scans in the text then analysis the digital images. • Used to automate postal sorting by recognising the postcode on the letters. • Some bills are created in a machine readable font.

10. Hardware Devices • Magnetic Stripe Reader • Reads information encoded magnetically in a stripe on the back of a plastic card. • The particles on the magnetic strip is orientated in a way to encode binary data • Can store up to 2k of information

11. Hardware Devices • Smart Card Reader • Reads from plastic cards that holds an integrated circuit chip • The Chip contains a microprocessor, a small amount of ROM, a small amount of EEPROM, a small amount of RAM and a computer bus system. • The chip is provided power when it is inserted into the reader. • Like a computer the mini applications are loaded into the RAM from the ROM and EEPROM and the microprocessor executed the applications.

12. Hardware Devices • RFID Reader • Radio Frequency Identification • Uses radio frequencies to transmit data. • Receives data from a carrier without any physical contact. • Data capacity of RFID transponders is normally a few bytes to several Kb

13. Hardware Devices • Touch Sensitive Screen • A VDU that allows user interaction with an application on the display. • Screen has been specially adapted so that the region just in front of the screen is criss-crossed by horizontal and vertical beams of infrared light. The breaking of these beams determines where on the application has been selected. • The coordinates of the broken beams is determined and sent back to the application. • The application maps these coordinates into an action. • Also uses a accelerometer to determine at what angle the device is held.

14. Hardware Devices • Graphics Tablet • Allows graphics to be drawn into the computer by hand like using a pencil. • Consists of a flat board and a stylus. • Pressing the board with the stylus operates a microswitch which is detected by the computer. • The boards contains electronics to detect the position of the stylus tip.

15. Hardware Devices • Voice recognition • The computer can be trained to recognise a human voice and transforms speech into text using a microphone, sound card and appropriate software • This system can be used to issue commands to the computer and to dictate sentences directly into applications.

16. Hardware Devices • Digital Still Camera • An electronic device used to capture and store photographs digitally on a memory cards before uploading to a computer via an USB Connection. • Can also record sound and video.

17. Hardware Devices • Output Methods and devices • Visual Display unit • Cathode – ray tube • Flat Screen • Plasma Screen • Speech Output • Electronic Paper • Printer • Impact Printer • Inkjet Printer • Laser Printer • Plotter

18. Hardware Devices • Visual Display Unit - CRT • A vacuum tube with a narrow neck and a flat rectangular base • Screen inside coated with a phospher that emits light when struck with an electron beam • The electron beam starts at the top and does line by line to the bottom. • Whole process is done many times per second. • If the process is completed in less that 0.05 seconds the human brain does not register any flicker. • Colour CRTs use three electron beams – The screen consists of triplets of phosphers – Red, Green and Blue. • The intensity of the light from the beams produce the colour.

19. Hardware Devices • Visual Display Unit – Flat screen • Liquid crystal Display is a matrix of liquid crystals cells • The liquid crystal changes the polarisation of light when an electric field is applied to the screen • Each cell consists of 1 pixel at full resolution. Each pixel is subdivided into RGB. • TFT (Thin Film Transistors). Each pixel is made up of a TFT, a capacitor and the liquid crystal. Transistor acts as a switch, and the capacitor as a reservoir for the electrical charge needed to create the electric field that changes the polarisation of the light passing through the liquid crystal.

20. Hardware Devices • Visual Display Unit – Plasma Screen • Each pixel is controlled by a miniature fluorescent light • When the control voltage is applied, the gas becomes plasma and releases ultraviolet light, which strikes phospers on the front of the screen to emit visible light. • Generates a lot of heat.

21. Hardware Devices • Speech output • Words in electronic documents can be output as spoken words using specialist speech synthesis software, a sound card and speakers. • Electronic Paper • Flexible paper thin displays which create images using tiny coloured beads that move or rotate in response to an electric field. • An electrically charged pencil can be used to write on the display. • Fed through a device that erases the image and writes a new page.

22. Hardware Devices • Impact Printer. • Used in applications that require multi-part stationary or printing through carbonised envelopes • Use an inked ribbon to mark paper with an impression of a character • Dot matrix printer uses 24 metal pins that form the outline of a character • Very noisy • Pin Number printing – the ribbon is removed so that the impact is shown but not the ink.

23. Hardware Devices • Inkjet Printer. • Printers that transfer ink to paper using electrostatics or non-impact technique • Colour printers print a line of colour at a time until the entire line is complete. • Colour printers use four ink cartridges – Cyan, Magenta, Yellow and Black. These colours are mixed at the right quantities to produce the desired colour – subtractive mixing. • Special paper is required for higher quality prints to absorb the ink.

24. Hardware Devices • Laser Printer. • Prints a whole page at a time, • Processor in the printer generates a bitmap of the page to be printed. • A negative charged is applied to the photosensitive drum at the heart of the laser printer. • One or more lasers are directed at the drum surface effectively drawing the image onto the drum neutralising the negative charge. • The charged surface of the drum is exposed to toner. The particles are negatively charged so they attach to the neutralised part of the drum. • A piece of paper is passed under the drum and pressed causing the toner to make the image on the paper. • Heated rollers fuse the toner to the paper which is why the paper comes out warm. • Colour laser printers have several drums.

25. Hardware Devices • Plotter • A output device that moves a pen across paper in a continuous movement so that a two dimensional drawing can be made. • The pen is lifted and placed when required. • Pens of different colours are placed to the side and are picked up by the drawing arm when required. • Perforated paper is placed over a drum in some instances and moved back and fore in the plotter to produce certain shapes – e.g. Circles.

26. Hardware Devices Your Task Using online mind mapping software (https://bubbl.us/) or shapes in power point create a mind map of the devices you have learned about that follows this format.