3.2 (C) Output Devices Flashcards
What is an actuator
an output device that converts electrical energy
into mechanical movement
What is a solenoid
Coverts electrical signal into magnetic field producing linear motion.
Types of motion caused by actuators
Rotary
Linear
Types of projectors
DLP - digital light projector
LCD - liquid crystal display projector
What is a dmd, full form, how it works.
A chip that uses millions of tiny mirrors on its surface to create a video display
Digital micromirror device
When the mirrors tilt towards the light, they are on. vice versa
This creates a light or dark pixel on the projection
screen.
The micro mirrors can switch on or off several thousand times a second creating various grey shades
How many shades of grey can be produced by micromirrors
1024 normally
How does the DLP projector work and how many colours
A bright white light passes through a colour filter.
The white light is split into the primary colours
The ON and OFF states of each micro mirror are linked with colours from the filter to produce the coloured image.
Can produce over 16 mil colours.
How does an LCD projector work
Powerful beam of white light is generated from a bulb or LED inside the projector body
this beam of light is then sent to a group of dichromic mirrors; these reflect the light back at different wavelengths, sep’ing the colours
these three different coloured light components pass through three LCD screens which produces a monochromatic image
The 3 images (red, blue and green images) are recombined to produce a colour image
Image passes through a lens onto a screen
Adv of a DLP
Higher contrast ratios
More durable
Quieter running than an LCD
Smaller and lighter
Disadv of a DLP
Don’t have grey components in image
Colour saturation compared to LCD proj is lower
Adv of an LCD proj
sharper images than a dlp
better colour saturation
more efficient in energy use and gen less heat
Disadv of an LCD proj
Limited life span
Degrade over time
2 types of printers
Inkjet
Laser printers
What is an inkjet printer made out of
A nozzle that sprays droplets of ink onto the paper to form the letters
Ink cartridge(s) - yellow, magenta, blue
Stepper motor and belt, moves the print head across the page.
Paper feed - automatically feeds paper into the printer
2 Types of inkjet tech
Thermal bubble
Piezoelectric
What is thermal bubble (inkjet)
Tiny resistors heat the ink up. This causes the ink to expand into a bubble. Ink is ejected onto the paper. A vaccum is created when the bubble bursts which allows fresh ink to be drawn from the vaccum
What is piezoelectric
Crystal is located at the back of the ink reservoir for each nozzle. The crystal is given a tiny electric charge which makes it vibrate. This vibration forces ink to be ejected onto the paper.
Process of an inkjet printer
Doc sent to printer driver
Printer driver makes sure doc can be understood
The printer driver checks to make sure the printer can print (busy, out of paper, available, etc)
Data is sent to temp memory of printer called printer buffer
Sheet of paper is fed into the paper.
As the sheet goes through the printer, the printer head moves from side to side across the paper printing the text or image
This process repeats until the data in the printer buffer is empty
The printer sends an interrupt to the CPU for more data to be sent to the printer
Process repeats until entire doc is printed
What is a laser printer
Uses dry powdered ink instead of liquid ink.
Uses static electricity to produce texts and images
Can print entire sheet in one go.
4 toner cartridge: blue, cyan, magenta, black.
What are 3D printers used for
to produce solid objects that actually work
Two types of binder 3D printing
Additive - adding materials layer by layer
Subtractive - removing materials layer by layer
What is binder 3D printing
Uses two passes for each of the layers; the first pass sprays dry powder and then on the second pass a binder (a type of glue) is sprayed to form a solid layer.
What is Direct 3D printing
uses inkjet technology; a print head can move left right up and down to build layers.
How to create an object using a 3D printer
Make a CAD design
The drawing is imported to a software that prepares it in a format that the 3D printer can understand
The 3D printer is first set up to allow the solid object to be made
Then the object is built up in layers.
Object is prepared and left to cure after it has been made
Uses of 3D printing
Prosthetic limbs
Reconstructive surgery (face surgery) - is more precise since they can fit the skull exactly
Aerospace - lightweight and precision parts
Fashion and art
Making parts that are no longer in production
CT scanner - full form and def
computed tomographic scanner – Can 3D image of a solid object by slicing up the object into thin layers (tomography)
What is an LED screen
A screen made up of tiny light emitting diode which are either red, green or blue in colour.
How does an LED screen produce diff brightness and colours
By varying the electric current send to each LED
Use of LEDs
Large outdoor displays
What is an LCD screen
Screens made up of tiny liquid crystals which make up an array of pixels that are affected by changes in applied electric fields
What does an LCD screen require to work
A backlight since the crystals cant produce any light themselves.
What is CCFL (LCD)
cold cathode fluorescent lamp - Back-lit method LCD uses.
How does CCFL work (LCD)
CCFL uses two fluorescent tubes behind the LCD screen which supply the light source
How do LEDS backlight LCD screen
A matrix of tiny blue-white LEDs is used behind the LCD screen.
Why LED backlighting better than CCFL
Max brightness reached immediately
Whiter light that sharpens the image and makes the colours appear more vivid; CCFL had a slightly yellowish tint
Brighter light - better colour definition
More durable
Consume little power - produce less heat and consume less energy
OLED full form
Organic Light emitting diode
What does OLED use
Uses the movement of electrons between a cathode and an anode to produce an on-screen image;
it generates its own light so no backlighting is required
Where is the organic film sandwiched in an OLED
Between two charged electrodes (one is a metallic cathode and the other a glass anode).
When does an OLED give light
when an electric field is applied to the electrodes
Layers of OLED
Glass Metallic Cathode (negative charge) Emissive layer Conductive layer Glass anode (positive charge) Glass or plastic bottom layer
ONE BIG IMP CHARACTERSITIC OF OLED
Very thin screens - can even be folded
Advantages of OLED
Thinner, lighter and more flexible
Give brighter light
Do not require backlighting
Very large field of view - about 170 degrees
What is a speaker
Output device that produces sound
How does a speaker output sound
Digital data passed through a DAC - changed to electric current
Electric current passed through an amplifier to make it large enough to drive to a loud speaker
Loud speaker converts electric current to sound
How does a loudspeaker convert electric current to sound`
The electric current flows through a copper coil which wraps around an iron core, making it a temp electromagnet. A perma magnet is positioned near the electro magnet
When the electro current varies, the magnetic field of the iron core varies. The iron core is attracted to the perma magnet and the variation causes vibrations
The iron core makes the cone attached to it vibrate, which produces sound waves.
