Computer Science 2210

Output Devices


Output Devices

Output Devices

• Output devices can be described as the devices that are used to show the information processed by a computer system in a human-readable form.

• The information shown by output devices can be in text, graphics, video, audio, etc.

Different Output Devices:

1. Printers

2. 2D & 3D cutter

3. Headphones & speakers

4. Actuators

5. Flat-panel display screens

6. Projectors


Inkjet Printers:

• Inkjet printers are usually used in homes and small offices for printing less volume of papers.

• It has a moving head that prints characters by spraying droplets of liquid ink on the ribbon from the cartridge.

• These printers produce less noise and use thermal bubble technology for the spraying of droplets.



Produces less noise.
Not suitable for high volume printing.
Good for printing images.
The moveable head is prone to clogging and damage.
No warmup time and reasonably fast.
Replaceable ink cartridges are expensive.

Laser Printers:

• Laser printers are usually used in offices where bulk volume printing is required.

• Unlike inkjet printers, they use a powder ink cartridge and uses static electricity for printing.

• The light is used to scan across the printing drum inside the printer in a back and forth direction.

• This scanning of light forms static electricity that attracts toner (powdered ink) to the paper.

• A fuser unit is used to bond the ink to the paper.



Produce high-quality print compared to inkjet printers.
It takes more space as compared to inkjet printers.
It produces a high volume of prints in very little time.
The toner is more expensive as compared to inkjet cartridges.
The cost per page is cheaper as compared to inkjet printers. 
If damaged; it is expensive to repair.

3D Printers:

• 3D printing is also known as additive manufacturing.

• 3D printers are devices that are used two produce three-dimensional products or prototypes.

• These printers print by laying up material from the ground until the final product is printed from a 3D computer model.

• The 3D computer model can be created using a 3D scanner as well as by using CAD modeling software.

• 3D printers are assisting in medical aids, prototyping, human prosthetics, etc.



It minimizes waste as it uses up a product that is required for production only.
Only a limited choice of material can be used for production.
It is cost-effective and inexpensive compared to traditional prototype production methods.
A large volume of production is not cost-effective compared to injection molding.
It can produce light yet stronger parts. 
The layered structure produced by these printers can delaminate under some circumstances.


2D Cutters:

• It is an output device that cut holes or shapes on a 2D flat surface.

• It can be a paper cutter or an industrial metal cutter.

• The cutter uses a laser to cut through different materials and different thickness surfaces without the need to change the machine.

• It provides precision cutting cost-effectively.

3D Cutters:

• 3D laser cutters are like 2D laser cutters but they can cut at many different angles.

• There are different types of 3D cutters available and some do not use a laser to cut through the object.

• These cutters have the ability to cut beneath the object's surface without scratching or damaging.

• The surface beneath cutting is typically done in glass or crystals.

Speakers and Headphones

• Speakers and headphones are both used for producing sound as an output.

• Speakers produce the sound that can fill the room whereas, headphone keeps the sound to one wearing it.

• These output devices produce sound by converting the digital signals into analogous sound waves.

• These sound waves are audible to human ears.

• These output devices can be used to hear music as well as to communicate and listen to other people.


• Actuators are used in robotics and control systems.

• These are output devices often control the movement in the real world by taking a signal from the microprocessor.

• For example, automatic mall doors.

Flat-Panel Display


• These are the most common form of output devices.

LCD Screens:

• In LCD screens, the display is created by combining gree, blue and red light filters available in each pixel.

• In a single LCD screen, there are millions of pixels (tiny blocks) available.

• Showing display is possible in LCDs because each pixel has liquid crystals that can be manipulated to allow fluorescent tube backlight in controlled proportion via the RGB filters on the screen front.

LED Screens:

• These are similar to LCD screens however, the light source in both is different.

• In LED screens, small LED bulbs are responsible for providing the light.

• In some screens, the entire display unit back is covered with these bulbs and in other models, only the edges have these bulbs.

• The screens with only edges bulbs are thinner.

• LED screens are power efficient in comparison to LCD screens.


• Projectors are output devices that show the display over the wall or large screen from a computer system.

• Projectors are best used during presentations or class lectures.

• Prices vary for different projectors; small projectors are reasonable but projectors capable of displaying movies in cinemas are expensive.

LCD Projectors:

• In LCD projectors, a high-density light beam passes through the LCD to the screen or wall.

• In a projector, there is a LED/ bulb from which a powerful white light is generated.

• A group of chromatic coated mirrors is used to reflect this white light at different wavelengths.

• The reflected light has wavelengths equal to RGB.

• These three different light wavelengths, show the image to be displayed in greyscale and with the help of the colored light that passes through the LCD, a colored version emerges from the greyscale images.

• Using a special prism, these images are then combined and the projector lens displays the image on the wall/screen.

DLP Projectors

• Unlike an LCD projector, it uses a fast-spinning color wheel filter.

• The filter is responsible for splitting the lamp light into RGB light.

• A bank (chip) made up of thousands of microscopic mirrors (pixels) is used to project the image.

• The color wheel filter and mirrors are synchronized to turn away or towards the light as required.

• The image is then magnified and projected out of the sense on the screen/wall.

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