Difference between emissive and non emissive displays in computer graphics
Answers
Emissive displays are devices that convert electrical energy into light; where the image is produced directly on the screen.
Examples for emissive displays are: Light Emitting Diode (LED), Vacuum Fluorescent Display (VFD), Plasma Display Panel (PDP),....etc
Non-emissive displays use optical effects to convert sunlight into graphical patterns and shapes; where the light is produced behind the screen and the image is formed by filtering this light.
An example for non-emissive displays are: Liquid Crystal Display (LCD).
Answer:
Emissive display is device that convert electrical energy into light. like ELD,LED etc
Non Emissive is a device that convert sunlight energy into light. like LCD
Explanation:
Emissive and Non-Emissive Display
Emissive Display
Emissive display is device that convert electrical energy into light.
Image is directly produced on the screen. Phosphorus convert electron beam or UV light into visible light.
1. Plasma Panel
A plasma display is a computer video display in which each pixel on the screen is illuminated by a tiny bit of plasma or charged gas, somewhat like a tiny neon light.
Working of Plasma Panel
The space between two glass plates is filled with neon-based gas and sealed. By applying voltages between the electrodes, the gas within the panel is made to behave as it was divided into tiny cells, each one independent of its neighbors. These independent cells are made to glow by placing a firing voltage of about 120 volts across it by means of electrodes. The glow can be sustained by maintaining a high frequency alternating voltage of about 90 volts across the cell. Due to this Refreshing is not required.
Advantages
• Large displays
• Good color rendering
• Thin panels
• No dependence on viewing angle
• Brightness
Disadvantage
• High Cost
• Power Consumption
2. ELECTROLUMINESCENT DISPLAY (ELDs)
An electroluminescent (EL) device is similar to a laser in that photons are produced by the return of an excited substance to its ground state. EL devices require much less energy to operate and do not produce coherent light
Layers of ELECTROLUMINESCENT DISPLAY
There are at least six layers to the device.
• The first layer is a baseplate
•The second is a conductor
•The third is an insulator,
•The fourth is a layer of phosphors
•The fifth is another insulator
•The sixth is another conductor
Characteristics
• Can be produced to any size or shape.
• Lightweight.
• Flexibility
• Strength -Almost unbreakable.
• Low power consumption
• Efficiency -80% of energy is converted to light.
• Brightness.
• Visibility
DISADVANTAGES
• Not practical for general lighting of large areas
• Poor lumens per watt rating
• Reduced lumen output over time,
• The lamps can use significant amount of electricity: 60-600 volts -
Light Emitting Diode (LED)
A light emitting diode (LED) is essentially a PN junction opto-semiconductor that emits a monochromatic (single color) light when operated in a forward biased direction. LEDs convert electrical energy into light energy.
Applications
• Sensor Applications
• Mobile Applications
• Sign Applications
• Automotive Uses
• LED Signals
• Indicators
Non-Emissive Display
Light is produced behind the screen and the image is formed by filtering this light.
Liquid Crystal Display
A Liquid Crystal Display (LCD) is a thin, flat panel display device used for electronically displaying information such as text, images and moving picture. LCD is used in Computer monitors, Televisions, Instrument panels, Gaming devices etc. Polarization of lights is used here to display objects.
How LCD Works
Liquid crystals are liquid chemicals in a state that has properties between those conventional liquid and solid crystals. That is a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way.
Advantages
• Lightweight Construction
• Thin Panels
• Low Energy Consumption
Disadvantage
• Quality of image depends on viewing angle
• Low response times