LED Lighting
Comparison of LED with Incandescent Bulbs and Compact Fluroscent Lights
About LED:
LED’s are tiny light bulbs that fit easily into an electrical circuit. They are illuminated solely by the movement of electrons in a semiconductor material, and they last just as long as a standard transistor. They are alternative to conventional lights. They don't have a filament that will burn out, and they don't get especially hot. They give of light in the visual or infrared spectrum, as electricity is passed through it.
Features of LED:
- Reduced maintenance and life cycle costs
- Low heat dissipation, Extremely long life spans
- Improved visibility, High luminous intensity, Vivid colors
- Significant resistance to shock and vibration
- Compatibility with integrated circuits and compact size.
- Reduces our greenhouse gas emissions that contribute to climate change and global warming.
Functionality of LED:
A Light-Emitting Diode (LED) is a semiconductor device that creates light using solid-state electronics and is made with alloy materials of aluminum, gallium and arsenide. A diode is composed of a layer of electron rich material separated by a layer of electron deficient material which forms a junction. Power applied to this junction excites the electrons in the electron rich material leading to photon emission and the creation of light. Different colors and different levels of brightness are achieved by altering the voltage of the electric power introduced into the diode.
Photons- Photons are the basic units of light and are released as a result of moving electrons. Photons are made up of many small particle-like packets that have energy and momentum but no mass.
A semiconductor has the ability to conduct electrical current at various levels. Most semiconductors are made of a poor conductor of electric current and has had impurities (atoms of another material) added to it. The process of adding impurities is called doping. “Doping” the material puts in free electrons or creates spaces for electrons to go into. This can make the material a better conductor. The material is either an N-type or a P-type, depending on whether it has added electrons or added holes.
Electrons – The negatively charged electrons in the semiconductor are called as N type material. The electrons move from negative to positive region.
Holes –The positively charged particles in the semiconductor have extra holes in it and are called as P type material. The electrons can jump from one hole to another hole and thus the holes emerge to be moving from a positive to a negative region.
Diode consists of two mutually bonded sections with electrodes on their sides. These sections are called as N type and P type material. The N type materials are connected to the negative end of the circuit and the P type material to the positive end of the circuit. The electrons in the n type material are repelled by the negative electrode and so moves towards the positive electrode whereas the holes move towards the negative electrode. When the voltage difference between the electrodes is high enough, the electrons in the depletion zone are boosted out of their holes and begin moving freely again.
Problems with existing Traditional lighting system:
- Traditional light sources such as mercury vapour, high pressure sodium (HPS) and low pressure sodium (LPS) have poor spectral content and colour rendering. This leads to visual fatigue and confusion when working with coloured wires, safety plaques, liquids, objects or smoke.
- Traditional fittings are susceptible to damage from shock and vibration. They are also often very large and therefore liable to damage from strong winds.
- The performance of traditional fittings is often limited in extreme environmental conditions, such as high and low temperature ranges.
- In traditional fittings there is a waiting time of up to 15 minutes for the lights to warm up and come to full brightness.
- Traditional lighting systems require frequent bulb replacement.
- Regular servicing of the traditional fittings also leads to moisture intrusion and deterioration of gaskets and other hardware.
- Traditional fittings are also typically very heavy and cumbersome, often requiring several workers to handle during installation.
- Reducing energy consumption has become a major challenge for industry and existing lighting technologies.