GCSE CS (2210) / IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.4 Output Devices
1. INKJET PRINTER
-A print head which consists of nozzles which spray droplets of ink on to the paper to form
characters
-An ink cartridge for each colour (blue, yellow and magenta) and a black cartridge or one
single cartridge containing all three colours+black
-A stepper motor and belt which moves the print head assembly across the page from side
to side
-A paper feed which automatically feeds the printer with pages as they are required
-Uses thermal bubble and piezoelectric technology to produce a hard copy
-Use hundreds of tiny guns to propel ink droplets on paper
-Characters printed are made up of drops of ink
-Ink tank supplies ink to an ink dispenser
-Drop of ink from the tank stays at the end of dispenser tube
-When a droplet is to be propelled, circuit energizes the piezoelectric crystal
-Crystal is pushed against a membrane which pushes it to the outlet of ink dispenser
-Droplet comes out from the dispenser onto the paper
-Application: photographs
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GCSE CS (2210) / IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.4 Output Devices
2. LASER PRINTER
-Differ greatly from inkjet printers in the way they print pages
-They use dry powder ink rather than liquid ink and make use of the properties
of static electricity to produce the text and images
-Unlike inkjet printers, laser printers print the whole page in one go (inkjet printers print the
page line by line)
-Electrically charged powdered ink is transferred onto paper
-Uses negatively charged images on a rotating drum
-and positively charged toner to output a hard copy
Inkjet Printer vs Laser Printer
-Inkjet are best for only a few pages of good quality, colored printing
-Inkjet has small ink cartridges and small paper trays
-Laser printers produce high quality printouts and are very fast when making multiple copies
of a document; any application that needs high-volume printing
(in color or monochrome) would choose the laser printer
-A large number of high quality flyers or posters would be ideal for laser printer
-They have large toner cartridges and large paper trays
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GCSE CS (2210) / IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.4 Output Devices
How a document is printed using a Laser Printer
-The printer driver ensures that the data is in a format that the laser printer can understand
-Data is then sent to the laser printer and stored temporarily in the printer buffer
-Has no moving head and uses static charge
-The printing drum is given a positive charge
-As the printing drum rotates, a laser scans across it
-this removes the positive charge in certain areas
-Negatively-charged areas are then produced on the printing drums
-these match exactly with the text and images to be printed
-The printing drum is coated in positively-charged toner
-This then sticks to the negatively-charged parts of the printing drum
-A negatively-charged sheet of paper is then rolled over the printing drum
-The toner on the printing drum is now transferred to the paper
-to reproduce the required text and images
-The paper goes through a fuser which melts the toner so it fixes permanently to the paper
3. 3D PRINTER
-They can produce solid objects which actually work
-The solid object is built up layer by layer using materials such as powdered resin, powdered
metal, paper or ceramic powder
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GCSE CS (2210) / IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.4 Output Devices
How a document is printed using a 3D Printer
-3D object of the file is made that needs to be printed made in Auto CAD
-one of the methods to print uses Selective Laser Sintering (SLS)
-uses a laser to fuse small particles of plastic/metal/ceramic
-into masses that has the desired three dimensional shape
-the laser then fuses the powdered material selectively
-A new layer of particles is spread out
-The next slice of design part is hardened and joined to the first
-then a new layer is applied on top of it and the process is repeated
-until the object is completed and is sandblasted
Applications
-printing prototype from CAD
-printing physical model from a blueprint
-building aerospace prototypes
-prosthetic limbs
4. 2D CUTTER
-High powered laser that uses the x-y plane
-to cut objects precisely
5. 3D CUTTER
-Similar to 2D Cutter but the laser can cut through x-y-z plane
-can be used to cut through glass, crystal, polymer
-not all materials that can be processed through 3D cutting can be used in 3D printing
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GCSE CS (2210) / IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.4 Output Devices
6.SPEAKERS & HEADPHONES
Speakers:
-Sound is produced from a computer by passing the digital data through a Digital to
Analogue Converter (DAC)
-Then through an Amplifier; finally the sound emerges from a Loudspeaker
-Outputs the sound produced by the computer to the user
-Used to listen audios, videos
Headphones:
-Can give instructions to user with motor disabilities or read text aloud
-Digital sound signals produced by computer passes through a Digital to Analogue Converter
-Then passed through an amplifier to make sound louder
-Output through speakers
7.ACTUATORS
-An electromechanical device i.e. motor, relay, valves, robot arm
-Allows a machine to operate
-Requires Digital to Analogue (DAC) converter to receive an electric signal
-Whereas a computer is sending a digital signal
-Used in process control i.e. greenhouse emissions, burglar system, autonomous cars
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GCSE CS (2210) / IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.4 Output Devices
8.FLAT PANEL DISPLAY
1. Liquid Crystal Display (LCD)
-Flat panel display that uses the light modulating properties of liquid crystals diodes
-Diodes are grouped together, known as pixels
-Three colors’ diodes are grouped together: red, blue, green (RBG)
-Modern LCDs are back-lit using Light Emitting Diode (LED) technology rather than the older
Cold Cathode Fluorescent Lamp (CCFL)
-CCFL provides the light to screen
-Essentially, CCFL uses two fluorescent tubes behind the LCD screen which
supplies the light source
-When LEDs arc used, a matrix of tiny LEDs is used behind the LCD screen
-Because LCD doesn't emit any light, some form of back-lit technology needs to be used
2. Light Emitting Diode (LED)
-LED stands for Light Emitting Diode
-instead of Cold Cathode Fluorescent Lamp (CCFL)
-this Flat panel display uses an array of light-emitting diodes as pixels
-to backlight the LCD panel
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GCSE CS (2210) / IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.4 Output Devices
Benefits of LCD being back-lit with LED instead of CCFL
-Reaches maximum brightness quickly
-Colors are vivid
-Good color definition/contrast can be achieved
-More reliable as LED’s are long lasting
-Consume very little/less energy
3. Organic Light Emitting Diode (OLED)
-Future LED technology
-These use organic materials (made up of carbon compounds) to create semi-conductors
which arc very flexible
-Organic films arc sandwiched between two charged electrodes (cathode and anode)
-When an electric field is applied to the electrodes, they give off light. This means that no
form of backlighting is required
-LCD would no longer be required as OLED is a self-contained system
Benefits of using OLED over LCD and LED
-The plastic, organic layers of an OLED are thinner, lighter and more flexible
than the crystal structures used in LEDs or LCDs
-The light-emitting layers of an OLED are lighter; OLED layers can be made
from plastic rather than the glass used in LED and LCD screens
-OLEDs give a brighter light than LEDs
-OLEDs do not require backlighting like LCD screens
-OLEDs generate their own light
-They use much less power than LCD screens
-Since OLEDs are essentially plastics, they can be made into large, thin sheets and could be
used on large advertising boards in airports, subways etc)
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GCSE CS (2210) / IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.4 Output Devices
9. PROJECTORS
1. Digital Light Projector (DLP)
-Uses a bright white light source and millions of micro mirrors on a chip
-To produce an image to be shone onto a wall or screen.
-The number of micro mirrors decide the resolution of an image
-Bright white light passes through a color filter before it reaches the DLP chip
-It’s split into RGB colors from which a 16 million color combinations possible
-When a micro mirror tilts towards the light source, they are on
-When a micro mirror tilts away from the light source, they are off
-The on and off states of each micro mirror are linked with colours from the filter to produce
the coloured image
2. LCD Projector
-White light propelled from the LED inside the projector
-Light reflected at different wavelengths by mirrors
-Those wavelengths represent RGB colors
-The 3 color components pass through 3 LCD screens
-Using these colors, grey images are converted into RGB colors
-Images then combined through a prism to produce full color image
-Colored image projected onto the screen
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GCSE CS (2210) / IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.4 Output Devices
SUMMARY
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