3.2 (C) Output Devices Flashcards by Neel Saraf

What is an actuator

an output device that converts electrical energy

into mechanical movement

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What is a solenoid

Coverts electrical signal into magnetic field producing linear motion.

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Types of motion caused by actuators

Rotary

Linear

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Types of projectors

DLP - digital light projector

LCD - liquid crystal display projector

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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

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How many shades of grey can be produced by micromirrors

1024 normally

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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.

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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

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Adv of a DLP

Higher contrast ratios
More durable
Quieter running than an LCD
Smaller and lighter

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Disadv of a DLP

Don’t have grey components in image

Colour saturation compared to LCD proj is lower

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Adv of an LCD proj

sharper images than a dlp
better colour saturation
more efficient in energy use and gen less heat

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Disadv of an LCD proj

Limited life span

Degrade over time

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2 types of printers

Inkjet

Laser printers

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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

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2 Types of inkjet tech

Thermal bubble

Piezoelectric

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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

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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.

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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

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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.