CFL LED Technology Presentation

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LED Vs CFL as efficient light sources A compilation by

Transcript of CFL LED Technology Presentation

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LED Vs CFL as efficient light sources

A compilation by

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Are LED Light Source Brighter Than CFL Light Source?

Some people say that LED's still aren't as bright as Compact Fluorescent bulbs. Some people say you should switch to LED's RIGHT NOW because they're way more efficient. So what's the

real answer? It depends...this compilation explains...

There's a push now towards "green" technology - alternative energy and finding ways for us to reduce our carbon emissions and reduce our dependency on foreign oil. One of the most promising

technologies are LED lighting.

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Spectrum Visible To The Eye As Light

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Break-down of Spectrum Visible to Human Eye

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Fixture efficacy

• In certain fixtures, an LED bulb actually gives out MORE light or is more efficient than CFL bulbs.

In this diagram, about half the light the CFL bulb is giving off is actually wasted and is reflected back in to the ceiling while with the LED, ALL the light is directed downwards where it's usable.

• So in this case, the efficacy of the bulbs while they are INSIDE the fixture -

• For LED's: 90 lumens per watt (lm/W)

• For CFL's: is reduced from 61 lumens per watt to 30 lumens per watt (lm/W) since half of the light is wasted.

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Lumen Output Measurement

LED's give directional light. This is unlike incandescent, halogen or compact fluorescent bulbs that give out omni-directional light (or light all around the bulb). The way that's normally been used to measure the efficiency and brightness of these bulbs is the lumen. You've probably heard of it or seen it on packaging. Another measurement is lumens per watt. Both of these measurements are poor ways to compare the brightness of LEDs to other types of bulbs (CFL, incandescent & halogen).

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How compact fluorescent lamps (CFLs) work?

When electricity flows into the electrodes, electrons (shown here as red dots) boil" from their surface and shoot off down the thin white tubes, which contain mercury gas, shown here as bigger blue dots. As the electrons hurtle down the tubes, they collide with atoms of the mercury. The collisions give the mercury atoms energy so their electrons jump to higher energy levels. But this makes the mercury atoms unstable, so the electrons quickly return to their ground states. When they do so, they give off photons of invisible ultraviolet light (slightly higher frequency than the blue light we can see), shown here as a purple wiggly line. If fluorescent lights make invisible light, how come they glow white? Here's the clever part. The thin glass tubes of a fluorescent light are covered in white-colored chemicals called phosphors. When the ultraviolet light strikes atom of the phosphors (shown here as gray dots), it excites their electrons in just the same way that the mercury atoms were excited. This makes the ph, fluorescent lights make their energy in a three-step process: 1. Electrodes take electrical energy from the power supply and generate moving electrons. 2. The moving electrons collide with mercury atoms in the tubes to make ultraviolet light. 3. The white phosphor coating of the tubes converts the ultraviolet light into visible light (that we can see).

Photo: The electronic circuit inside a CFL lamp. The transformer is the big orange/gold thing in the center. The black cylinder on the left is a capacitor. The four silver colored contacts on the extreme right are where the electrodes attach.

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20 Reasons to choose LED over CFL • Electrical Power Saving

LED lighting system saves electrical power, 80% compared with incandescent bulb, 50% compared with compact fluorescent lamp, 60% compared with fluorescent lamp, 75% compared with halogen lamp, 80% compared with mercury gas lamp, and 65% compared with high pressure sodium lamp.

• Durable Lifetime LED has lifetime up to 50,000 hours. System lifetime for LED lamp is over 20,000 hours. Compared with the lifetimes of other lamps, incandescent lamp has 1,000 hours, halogen lamp has 2,000 hours, fluorescent lamp has 2,000 hours, compact fluorescent lamp has 6,000 hours, mercury gas lamp has 8,000 hours, and high pressure sodium lamp has 12,000 hours.

• Green Material Usage Our LED lamps meet ETL and UL standards and contains no hazardous solid, liquid or gas. It does not contain mercury, cadmium, lead, chromium or xenon gas.

• Low Carbon Dioxide Release Prevent generating warming effect.

• No UV Light Does not destroy objects lighted, does not cause freckles and solar lentigines.

• No IR Light Does not radiate heat, demand less air conditioning.

• Cold Light Does influence plant growth.

• Selectable Color Temperature Warm white to cold white LED is available from 2,600K to 6,000K.

• Supreme Safety Low DC current and voltage.

• Direct Light No light pollution.

• No EM (Electromagnetic) and No RF(Radio Frequency) Does not cause Migraines.

• Anti-glazing Light diffusers or conductors integrated for anti-glazing and eye safety.

• Comfortable Light Pattern and Optimal Lumen Homogenous lighting, no light pressure.

• High Light Source and System Efficiency Performance of light source and system efficiency for LED lighting surpasses than any other traditional lighting.

• Low Maintenance Expense Long lifetime reduces replacement expense. Stable system reduces maintenance expense. Low power consumption reduces set up cost.

• Better CRI (Color Rendering Index) LED lighting has better CRI than mercury gas, high pressure sodium, low pressure sodium and HID lamps.

• Positive Health Effects Started in one milli-second, no glistening, no high power discharged for protecting eyes and brain.

• Colourful and Emotion RGB mixing and control for colourful and emotion lighting.

• Miniature LED Volume Shock resistant.

• No Light Decay in Extreme Low Temperature Fluorescent lamp and compact fluorescent lamp have highly lighting decay at low temperature.

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Compact Fluorescent Bulbs What You Didn't Know

CFLs contain mercury. • CFL bulbs contain small amounts of mercury which is toxic to

individuals, especially those that are still developing, such as children and pregnant women. This is an inherent part of the technology so you will never get a CFL bulb that doesn't contain mercury. Most CFLs contain about 3-5mg of mercury. Here's some excerpts from Wikipedia article on mercury exposure

• "A study has shown that acute exposure (4-8 hours) to calculated elemental mercury levels of 1.1 to 44 mg/m3 resulted in chest pain, dyspnea, cough, hemoptysis, impairment of pulmonary function, and evidence of interstitial pneumonitis.[37]"

• "Acute exposure to mercury vapor has been shown to result in profound central nervous system effects, including psychotic reactions characterized by delirium, hallucinations, and suicidal tendency."

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Physics – LED Technology

The LED consists of a chip of semiconducting material doped with impurities to create a p-n junction. As in other diodes, current flows easily from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction. Charge-carriers—electrons and holes—flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon.

The wavelength of the light emitted, and thus its color depends on the band gap energy of the materials forming the p-n junction. In silicon or germanium diodes, the electrons and holes recombine by a non-radiative transition which produces no optical emission, because these are indirect band gap materials. The materials used for the LED have a direct band gap with energies corresponding to near-infrared, visible or near-ultraviolet light.

LED development began with infrared and red devices made with gallium arsenide. Advances in materials science have enabled making devices with ever-shorter wavelengths, emitting light in a variety of colors.

LEDs are usually built on an n-type substrate, with an electrode attached to the p-type layer deposited on its surface. P-type substrates, while less common, occur as well. Many commercial LEDs, especially GaN/InGaN, also use sapphire substrate.

Most materials used for LED production have very high refractive indices. This means that much light will be reflected back into the material at the material/air surface interface. Thus, light extraction in LEDs is an important aspect of LED production, subject to much research and development.

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High-power light emitting diodes The inner workings of an LED

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LED - High Extraction Efficiency Structures

• Shaping of the LED die is critical to improve their efficiency.

• LEDs of various shapes; hemispherical dome, inverted cone, truncated

cones etc have been demonstrated to have better extraction efficiency

over conventional designs.

• However cost increases with complexity.

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The light emission cones of a real LED wafer are far more complex than a single point-source light emission. Typically the light emission zone is a 2D plane between the wafers. Across this 2D plane, there is effectively a separate set of emission cones for every atom. Drawing the billions of overlapping cones is impossible, so this is a simplified diagram showing the extents of all the emission cones combined. The larger side cones are clipped to show the interior features and reduce image complexity; they would extend to the opposite edges of the 2D emission plane

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White LEDs based on Phosphor Converters

A blue GaInN/GaN LED and a phosphor wavelength converter suspended in a epoxy resin make a white Light LED. The thickness of the phosphor containing epoxy and the concentration of the phosphor determine the relative strengths of the two emission bands

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Promise of Solid State Lighting - LED

• The use of solid state lighting devices promises huge savings in energy consumption.

• The electricity for lighting needs is 60 GW, over 24 hrs.

• About 24 GW year is consumed by incandescent lamps with a luminous intensity of 15 lm/W.

• 36 GWyear is consumed by FL/HID lamps with a luminous intensity of 75 lm/W.

• Assuming that by year 2020, they are replaced by LEDs with luminous intensity of 150 lm/W, energy savings are 40 GW year.

• That translates to $40 billion in savings.

• At 4 Mn tons / GW year of coal consumption, net savings lead to 25% less coal consumption, leading to lesser emissions of green house gases.

• Global savings are projected to be about $140B.

Roland Haitz, Adv. in Solid State Physics

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Thank you

Please visit the below link for more detailed

http://en.wikipedia.org/wiki/Light-emitting_diode#Physics