Hardware Devices Input methods and devices Mouse Keyboard

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

Hardware Devices Mouse ØDesigned in 1964 by Douglas Engelbart ØUse as a tool to aid use of Graphical user interfaces. ØUses a X-Y positioning system ØLatest mouse uses wireless technology and more buttons for different functions.

Hardware Devices Keyboard ØEnter text and numbers into a computer ØElectronic circuits continually scan the keys to detect key presses ØConverted to ASCII code or UNICODE for the computer to understand ØEach key press sent as an interrupt to the CPU Ø Braille Keyboards are used for disabled people.

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

Hardware Devices Scanner - Flatbed ØGlass plane illuminated from beneath by a bright light ØAn 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. Ø Converted into an equivalent electric signal. Ø Colours scanner have three arrays – Red, Green, Blue Ø A digitised imaged is stored by the computer.

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

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

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

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

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

Hardware Devices Smart Card Reader ØReads from plastic cards that holds an integrated circuit chip Ø 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. Ø The chip is provided power when it is inserted into the reader. Ø Like a computer the mini applications are loaded into the RAM from the ROM and EEPROM and the microprocessor executed the applications.

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

Hardware Devices Touch Sensitive Screen ØA VDU that allows user interaction with an application on the display. Ø 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. Ø The coordinates of the broken beams is determined and sent back to the application. Ø The application maps these coordinates into an action. Ø Also uses a accelerometer to determine at what angle the device is held.

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

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

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

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

Hardware Devices Visual Display Unit - CRT ØA vacuum tube with a narrow neck and a flat rectangular base Ø Screen inside coated with a phospher that emits light when struck with an electron beam Ø The electron beam starts at the top and does line by line to the bottom. Ø Whole process is done many times per second. Ø If the process is completed in less that 0. 05 seconds the human brain does not register any flicker. Ø Colour CRTs use three electron beams – The screen consists of triplets of phosphers – Red, Green and Blue. Ø The intensity of the light from the beams produce the colour.

Hardware Devices Visual Display Unit – Flat screen ØLiquid crystal Display is a matrix of liquid crystals cells Ø The liquid crystal changes the polarisation of light when an electric field is applied to the screen Ø Each cell consists of 1 pixel at full resolution. Each pixel is subdivided into RGB. Ø 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.

Hardware Devices Visual Display Unit – Plasma Screen ØEach pixel is controlled by a miniature fluorescent light Ø 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. Ø Generates a lot of heat.

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

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

Hardware Devices Inkjet Printer. ØPrinters that transfer ink to paper using electrostatics or non-impact technique Ø Colour printers print a line of colour at a time until the entire line is complete. Ø 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. Ø Special paper is required for higher quality prints to absorb the ink.

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

Hardware Devices Plotter ØA output device that moves a pen across paper in a continuous movement so that a two dimensional drawing can be made. Ø The pen is lifted and placed when required. Ø Pens of different colours are placed to the side and are picked up by the drawing arm when required. Ø 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.

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.