Output devices

Question 1

Define

output device

Answer 1

An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) which converts the electronically generated information into human-readable form

Taken from Wikipedia LAWL

Question 2

How does a inkjet printer work?

Answer 2

• Uses a printhead to propel droplets of ink from fine nozzles onto paper
• Printhead passes left and right across paper while roller feeds paper forwards

Question 3

List some advantages and disadvantages of inkjet printers

Answer 3

Advantages:

• Good colour production (good for printing pictures)
• Low purchase cost

Disadvantages:

• Ink is expensive
• Water-soluble ink smudged when damp
• Slow output rate

Question 4

How does a laser printer work?

Answer 4

• Uses a laser scanning a drum to print with powdered ink, called toner
• Printer paces an even, negatively static charge on a photoconductive drum
• Laser beam scanned on the rotating drum causes negative charge to leak away
• Drum revolves past negatively charged toner supply which is attracted to the regions on the drum where no charge remains

Question 5

List some advantages and disadvantages of laser printers

Answer 5

Advantages:

• High resolution and rate of output - useful when printing multiple copies of one sheet as the same pattern of negative charge is used
• Toner is not water-soluble, so does not get smudged when wet
• Toner is cheaper than inkjet printer ink

Disadvantages:

• Expensive to buy
• Toner is toxic
• Colour production not as precise as inkjet printers

Question 6

How does a 3D printer work?

Answer 6

• Makes a three-dimensional solid object of any shape from a digital model.
• Some 3D printers use inkjet technology.
• Others use lasers to fuse granules of plastic, metals, ceramic or glass.
• It can also be done by successive layers of material being laid down in different shapes.
• Construction of a model can take anywhere from several hours to several days, depending on the method used and the size and complexity of the model.

Question 7

List some advantages and disadvantages of 3D printers

Answer 7

Advantages:

• Can produce a wide variety of manufactured products, including customisable products and personal designs
• Rapid prototyping
• Fast manufacturing of printed products
• Even though the initial setup costs are higher, 3D printing is becoming cheaper than cheap labour in third world countries
• More Jobs: engineers to design and build 3D printers, technicians to maintain, use, and fix 3D printers
• Potential in medicine to print customisable human body parts or organs

Disadvantages:

• Currently, 3D printers only manufacture products out of plastic, resin, certain metals, and ceramics.
• Printing of copyrighted products to create counterfeit items will become more common and nearly impossible to determine.
• Easy to print dangerous items such as guns or knives
• Currently, 3D printers are limited with the size of the products that they can create

Question 8

How does a 2D cutter work and where may it be used?

Answer 8

• Use laser to cut precise patterns in most materials
• Approx. 20mm limit for depth of the cut
• Used in industry, for example to cut a sheet of metal

Question 9

List some advantages and disadvantages of 2D cutters

Answer 9

Advantages:

• Quick way to cut through many different materials

Disadvantages:

• The laser cutter can only cut on a single flat face and does not recognize the other faces of an object like a 3D cutter

Question 10

How does a 3D cutter work and where may it be used?

Answer 10

• A three-dimensional laser cutter is like a regular laser cutter, except the laser is able to recognize all sides of a shape and not just the shape’s face.
• Can be used to make models of objects

Question 11

List some advantages and disadvantages of 3D cutters

Answer 11

Advantages:

• Can cut many different types of materials, such as glass, crystal, metal and wood.
• Can be set to cut the inside of the material, allowing more complex shapes

Disadvantages:

• Ordinary 3D cutters using a rastering motion do not allow for 3D shapes of the sort that have ledges or require undercutting, or any kind of cutting/machining that can’t be done from vertically above and perpendicular to the X-Y plane.

Question 12

How do speakers and headphones work?

Answer 12

• An electromagnet causes a diaphragm to vibrate depending on the electrical current. The diaphragm’s vibrations causes the air to vibrate, which produces sound
• Headphones and earphones are small versions of speakers designed to fit on or in your ear, used to prevent other people from hearing private content

Question 13

What are actuators?

Answer 13

• An output device used for controlling a system, though it does not always provide output directly to the user
• Usually paired with sensors that provide feedback to the control program
• Actuators can act to affect the real-world depending on the signal or reading received

Question 14

What are flat panel display screens?

Answer 14

• Very thin display screens
• Small, light and easy to fit on a table or mount on a wall
• The screens are backlit to make it easier to read
• Different types include:
  
  • Liquid Crystal Display (LCD)
  • Light-Emitting Diodes (LED)

Question 15

How do Liquid Crystal Display (LCD) screens work and where may they be used?

Answer 15

• Uses two sheets of material with a liquid crystal solution between them
• Monitor’s control program scans and sends signals to individual liquid crystal pixels to allow certain amounts of light and colour to pass through
• Used in some types of digital watches and PCs

Question 16

List some advantages and disadvantages of LCD screens

Answer 16

Advantages:

• Sharp images
• Zero geometric distortion at the original resolution of the screen
• Bright images - best for brightly lit environments.
• Consume little electricity and produce little heat
• Immune to screen image burn-in

Disadvantages:

• The colour and contrast from various viewing angles is inconsistent
• Poor colour production of black and very dark grays - not suitable in darker environments
• Motion blur is common
• With brightness from backlighting, imagery may appear flat
• Pixel-based display may be stuck on screen
• Fixed resolution
• Newer technology costs more

Question 17

How does an LED screen work and where may it be used?

Answer 17

• Stands for Light Emitting Diode
• A diode that glows when voltage is applied as the result of moving electrons
• Allows the flow of current in a single direction only
• Typically used outdoors in store signs, billboards or information screens

Question 18

List some advantages and disadvantages of LED screens

Answer 18

Advantages:

• LEDs are much smaller than LCD fluorescent lamps so the screen itself can be made thinner and lighter — good for mobile phones
• LEDs are high-efficiency light sources, and low power consumption leads to significant energy savings
• Switch on rapidly, even when cold

Disadvantages:

• The colour of white LEDs can be very inconsistent

Question 19

How does an LCD projector work and where may it be used?

Answer 19

• An LCD projector is a video projector used to display images, videos and computer data on a screen or other flat surface
• LCD projectors send light through a prism that separates light into three panels, red, green and blue components of the video signal
• The images stack on each other on the screen to produce the image
• Used in home theatres, school classrooms, etc.

Question 20

List some advantages and disadvatages of LCD projectors

Answer 20

Advantages:

• Can achieve greater brightness at a lower energy consumption
• Sharp image
• Possible to achieve greater zoom magnification with an LCD projector

Disadvantages:

• Because there are three panels, it is possible for one to fall out of alignment. This will cause one of the three stacked images to be shifted slightly.
• Filters need to be cleaned periodically, causing an LCD projector to be more maintenance intensive

Question 21

How does a DLP projector work and where may it be used?

Answer 21

• Stands for Digital Light Processor.
• Uses a digital micromirror device, where microscopically small mirrors are laid out to create the image.
• In a single chip DLP projector, colours are produced either by placing a colour wheel between a white lamp and the DLP chip or by using individual light sources to produce the primary colours, e.g. LEDs or lasers.
• A three-chip DLP projector uses a prism to split light from the lamp, and each primary colour of light is then directed to its own DLP chip, then recombined and directed out through the lens.
• Used in some cinema systems and large venue projectors.

Question 22

List some advantages and disadvantages of DLP projectors

Answer 22

Advantages:

• Unlike LCD projectors, DLP screens do not rely on fluids and are therefore not limited in size by their inherent mirror mechanisms, making them ideal for increasingly larger high-definition theatre and venue screens.

Disadvantages:

• May use more electricity, and generate more heat, than competing technologies.
• People may be bothered by the “rainbow effect”, particularly in older models.