Energy-saving bulbs

Structure

Inside the glass tube of the lamp is an inert gas, either argon or a mixture of argon and krypton, at a pressure of only about 0.2% of atmospheric pressure. Also in the tube is a very small quantity of mercury between 3mg and 15mg depending on the size and type of the lamp. Mercury is a metal and liquid at normal room temperature, but inside an operating lamp which is hot, the mercury is in a vapor form, but its vapor pressure is extremely low in fact only about 0.0007% of atmospheric pressure. Fluorescent tubes and Energy saving lamps are technically referred to as 'low pressure gas discharge lamps'.

At the ends of the tube are electrodes - usually referred to as cathodes - which are electrically heated tungsten coils coated with Barium Oxide which when hot, have the property of releasing electrons.

Operation

When the lamp is started, the cathodes are first heated for a short time (1 to 2 seconds) in order to heat the cathodes so they release electrons. A high voltage is then applied across the two cathodes and a discharge is created as the gas and mercury vapor conducts the electrical current. The flow of electrons (i.e. the current), energizes the vaporized mercury atoms to make them give off ultra-violet (UV) radiation. The inside of the glass tube is coated with a fluorescent powder, which is referred to as the 'phosphor'. The UV radiation makes the phosphor give off visible light but only whilst exposed to the UV (i.e. the process of fluorescence).

The discharge in the argon or argon/krypton gas causes the gas to give off a bluish glow, which can only be observed in a tube without the phosphor coating. This light constitutes only about 3% of the total light output from the lamp, the remaining 97% is generated by the phosphor.

Ballast

Energy saving lamps are not designed to be operated directly from the mains supply.

All lamps require a device to generate a high voltage (more than 230V) to initiate the discharge and an additional device to control the discharge current. Unlike incandescent lamps, fluorescent lamps cannot on their own control the current and would draw such high currents from the mains that they would destroy themselves.
These devices are collectively referred to as 'ballast'.

HOW DO THE LEDs WORKS?

At the heart of every LED there is a very small piece of semi-conducting material called the LED ‘die’. The die can be considered in the same way as the filament in a lamp, because it is the die that produces the light. The size of a high power LED die is approximately a 1mm cube and for other LED types much smaller.

The base of the die is glued or soldered into a fine metal framework (the leadframe). A very fine wire called a bond wire is attached to the top of the LED die, which has a very fine conductive metal pattern on it. The wire is attached to the other side of the leadframe.

LED stands for Light Emitting Diode. LED's are now found on almost every electronic device including MP3 players, DVD players, TV's, clock radios and computers. LED's have been popular for decades, however today they are cheaper, brighter and come in more colors than ever before. While the incandescent light bulb has been the light of choice for at least 100 years, many believe the LED will soon replace it. Here is how LED light bulbs work:

What is an LED Light Bulb?

LED's are very similar to traditional light bulbs, except that they fit directly into an electrical circuit. LED's do not have a filament, so they generally last for a long, long time without burning out. Because there is no filament, LED's do not get hot and require far less electric power than traditional light bulbs due to their efficiency. In fact, LEDs are illuminated by electrons that run through the semiconductor material that LEDs are connected to.

What is a Diode?

An LED is a light emitting diode. A semiconductor diode is a two-terminal device, sometimes described as a pn. An LED is fabricated from a semiconductor material. One side of the semiconductor is attached to the P side which is the anode; the other side of the semiconductor is attached to the N side, the cathode. Electricity can flow from the p side to the n side. However, no electricity can flow in reverse. In effect, therefore, a diode is a unidirectional conductor.

Components of an LED Light

Common components of an LED include: A whisker which is connected to the anode, the anvil, which is connected to the cathode, a lens to illuminate the light created for distances and a high impact plastic casing to protect the LED.

The Color of an LED Light

LEDs are available in a variety of colors. While popular colors include red, yellow and green, one of the most difficult colors to create is white. In fact, it is currently not possible to create pure white for mass production. Most LED flash lights or light bulbs today that are white in color are actually not pure white, but whitish-blue.

LEDs Offer Many Benefits

There are many reasons why LED Light bulbs continue to be popular. Here are some of the main benefits they offer:

• LEDs are extremely efficient and require very little current to illuminate. Since they do not have a filament, LEDs don't heat up, making them perfect for many electronic applications where heat is detrimental. In a traditional light bulb, the vast majority (sometimes more than 80%) of the electricity used to illuminate a light bulb is wasted not in light, but in heat.
• LEDs are manufactured within an epoxy resin epoxy, which means that that they are virtually indestructible. Compared to a traditional light bulb, an LED is far more durable.
• LEDs can be mass produced. Just like traditional light bulbs, they are extremely affordable to produce in large numbers.
• LEDs are considered to be solid state devices. Solid state refers to any item that has no moving parts. When an item has no moving parts, it is generally more reliable because of less friction and fewer parts that can malfunction.

Basic features:

• Lowest power consumption
  With LED technology almost all the energy in flashlights is converted into light, while traditional light bulbs convert the majority of the electricity into heat, less into light. LED lighting is 90% more effective than traditional and halogen light bulbs. In comparison, traditional incandescent 60W light bulb = halogen 60W light bulb = fluorescent 14W light bulb = LED 7W light bulb at the same lighting level. LED analogs of most commonly used incandescent lamp use from 0.83 to 7.3 watt power.
• Durability
  LED lighting duration lasts from 50.000 to 100.000 hours. That means that LED light bulbs can illuminate for 20 years by using it 8 hours a day. Meanwhile traditional incandescent bulbs illuminate for ~2.000 hours. This feature of LED light bulbs is very important when bulb replacement is costly enough, that is in hardly accessible places.
• Small dimensions
  LED light bulb sizes range starting with several millimeters for flashlights to the size of a traditional streetlight.
• Solidity and resistance
  LED light bulbs are resistant to temperature and mechanic affect as well as vibration. They can illuminate at ambient temperatures from -40°C to +185°C and LED light bulbs are extremely suitable where light is frequently turned on and off, e.g., garage, basement, etc.
• Widest colour use possibilities
  LED for flashlights are manufactured in all possible colour combinations - white "warm" colour (from 2700K to 3500K), "clean" white (from 5000K to 6500K), "cold" white (up to 8000K), amber, orange, red, cyan, blue, green and no colourful filters are used. This allows LED lights to be widely applied in decorative lighting.
• Ease of control and extinguishing
  LED lights retain their lighting colour during the extinguishing (unlike incandescent light bulbs, which have a yellow light). Feeding voltage of LED light bulbs ranges from 12V DC to AC 86V-265V. There is no need to use ballasts or high frequency converters, which jam radio and TV signals. Low feeding voltages increase light bulb usage safety and allow for the use of these light bulbs in hazardous places – pools, gas station, etc.
• Least harmful for people and environment
  LED lights do not emit UV radiation harmful for eyes (unlike the energy saving luminescent light bulbs) and do not emit heat. LED lights do not emit IR and UV radiation, therefore it is extremely suitable for outside lighting, since UV radiation attracts insects. LED does not contain hazardous gases or mercury. LED lights do not heat up and burn in case of an accidental contact.
• Wide application and use
  LED light bulbs are widely used for interior lighting, building exterior decorative lighting, garden and yard lighting, plant lighting in greenhouses, street lighting, etc.