Output Devices

Output Devices: 

Output Devices

Plasma Screen: 

A plasma screen is a display that contains cells which contain electrically charged ionized gases for each pixel, these are commonly known as fluorescent lamps. When the controlled charge is applied to the cells, they become plasma and release ultra-violet light, which hit phosphors (releases light without heat). Plasma Screen

LCD Screen : 

A liquid crystal is a substance which is nether solid or liquid however they can be changed with electrical currents. Each pixel contains a tiny transistor, capacitor and a liquid crystal. The transistor acts as a switch and the capacitor contains the electrical charge. The charge sent through the crystal changes the light that will pass through it. LCD Screen

Inkjet Printer: 

A inject printer contains cartridges of different colour inks. To eject a drop from the cartridge, a electric pulse needs to travel though a heating element causing the ink to vaporise which causes pressure increase, forcing a droplet of ink to inject into the paper. A inkjet printer will print one line at a time, so printing a line of characters will involve printing several lines of different colours, because the characters are recognizable. Inkjet Printer

Laser Printer: 

A laser printer contains a drum which is negatively charged at points where ink needs to go, ink which is positively charged then sticks to the negative parts of the drum. The paper is positively charged and is rolled through, and when it goes pass the drum and the ink is rolled onto it, then it goes into a fuser which heats the paper and fuses the ink and the paper together. It is called a laser printer because it contains a laser which scans the drum to know where ink should go and where ink is. Laser Printer

Dot Matrix (Impact) Printer: 

A dot matrix printer contains loads of small circular pins that hit a inked ribbon to form a character on the paper behind it. The paper is then rolled out. Because they are just loads of pins hitting paper, they make a lot of noise, however they are some of the most reliable printers and are highly durable. Dot Matrix (Impact) Printer

Plotter: 

A plotter is used to draw vector graphics by moving a pen or a group of pens across paper in a continuous movement. They are restricted to line art and solid blocks can not be drawn, however they can hatch a area with very close lines The pen is moved by a arm, receives a number of instructions from the computer or entered onto the machine. A plotter was originally programmed with a printing programming language and were based on English “place pen on paper”, however they could also be programmed with a basic-like language, for example 10 SCALE -1,1,1,1 20 FOR X =-1 to 1 STEP 0.1 30 PLOT X, X*X 40 NEXT X 50 PEN 60 END In the printer, the paper would be moved back and forth through a roler in the X axis, the pen would then be moved by the arm in the Y axis, the plotter would know where the paper was due to it having perforations on the side. Plotter

Electronic Paper (E-Paper): 

Titanium Dioxide particles are dispersed in oil which is dyed and charging agents. This mixture is placed between two parallel plates. When the voltage is applied, the particles will move to the plate bearing the opposite charge from that of the particles. When the particles are on the viewing side of the display, they appear white because the light is scattered back. When the particles are near the back, they appear dark because of the dye in the oil. Electronic Paper has a very low power requirement, and are paper like due to that they don’t need to power their own light because they use other light sources ( eg the sun), A disadvantage is that the refresh rate is very slow, meaning these can not be used on a computer because using a console, cursor or scrolling would be slow. The screen can also Ghost, causing its previous image to be shown over the current one, however this is fixable by refreshing the screen several times. Electronic Paper (E-Paper)