Drop the Hammer

According to Ed, a lot of work was done by GE in 1970′s, specifically by a man named John Anderson. He patented an electronic high frequency ballast which was technically successful, but not commercially successful because of very high costs. Therefore the technology was there at the time, but the cost made no sense to make them.

In 1973-74 the oil crisis took place and lamp companies needed to reduce wattage in their linear (tube) lamps to compensate. Many people had four bulb fixtures and were removing two bulbs, to save energy, therefore dropping sales by half. This forced lamp companies to create energy efficient solution.

Ed worked on creating lamp with reduced wattage by adding krypton and a conductive tin coating inside. This helped lower the wattage from 40 to 35 watts but he wanted to get down to 30 watts. He continued to work and finally the wattage went from 35 to 34 and eventually 32 watts!

Ed explains the different types of linear lamps – T8, T12, T5, T17. The conversion is 1 inch = 8/8 diameter. Therefore a T12 = 12/8 =1.5 inches in diameter, or a T8 = 8/8 = 1 inch in diameter.

The new lamps created a reliable start and higher range of ambiant light, using less energy.

In 1975 companies were still using old electronic ballasts which were failing, while the lamps were still good. This posed a problem for extending the life of the whole package. It was pointed out that the ballast and lamp have to be a system – the ballasts needed to catch up with technology the lamps had already reached.

Ed realized they would need a CFL for residential use. He came up with the idea to make the linear tube into a spiral. He was told that it would be too expensive and the reflection loss would be too great, basically that he should NOT waste his time.

He went ahead and made the spiral, and as long as he optimized the spacing between the spirals the reflection loss was minimized (at the most 3 lumens per watt). This still made the CFL lamps much better than the incandescent bulbs.

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Ed has made inert gas lamps in the past in order to try to eliminate the use of mercury. He replace the mercury in the bulbs with inert gases to create the correct color combination. The best lamp he could come up with in doing so created only 20-30 lumens per watt. This was better than the average incandescent light bulb, but therefore also had less than half the efficiency of a fluorescent lamp.

His next attempt was to remove the phosphor from the lamps and leave the mercury, thus using the light from low vapor pressure mercury. This caused the lamps to go from 75 lumens per watt to 7 lumens per watt, clearly not a solution. That is even less than an incandescent bulb’s lumens per watt.

Currently there are laws evolving around the use of incandescent light bulbs in the future. They are moving towards the regulation that bulbs used in the future need to be 30 lumens per watt or better. Currently incandescents do not fit this standard and a new type of incandescent bulb will need to be developed if they want to survive. The present initiative is for incandescent light bulbs to be phased out by 2012 in the US, and possibly 2010 in Europe.

LEDs vs. CFLs. LEDs have been suggested as a replacement to CFLs, since CFLs use mercury. LED lamps are NOT as efficient as CFLs. They do not work well as a general light source to replace incandescent bulbs like CFLs. LEDs do not have the same amount of lumens per watt. There are also heat issues with LEDs as they tend to get extremely hot. CFLs on the other hand remain cooler than even incandescent bulbs. LEDs are better for specific purposes, such as their current uses in flashlights or traffic lights. The light given off from LEDs does not make them suitable for reading light like fluorescent lighting that creates the full spectrum.

There are so many types of lighting to choose from today it can be difficult. There are incandescent light bulbs, CFLs, LED, HID. It seems that each type of light is better for different applications. The fluorescent lighting market is much more broad. Others have a more specific ‘best application’ such as LED lights for traffic lights or flashlights and HID lights for stadium lighting.

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Process of Heating the Filaments

The next topic Ed discussed moved to an electronic aspect and the optimization of the ballast. It is important when making the lamps to make sure the filaments are not heated too fast or too slow, as each would have a negative effect in the lamp. The rate at which the filaments are heated create the result of how fast the light will turn on.

There were limitations with the first electronic ballast. Scientists did not really know what a lamp did or did not need to properly function. Once the needed adjustments were finally realized the changes could be implemented into the design, which led the new ballasts being much better than the eletro-magnetic ballast could ever be.

Since 1938, when the first practical CFL was made, the process has always been the same to create them. The function of a CFL goes something like this: the filament is heated, the electrons jump off the filaments which caused them to bump into mercury atoms. The mercury absorbs some energy and gives off some energy in the form of photons, which then land on the phosphor to create visible light. This visible light can be made into different colors based on the composition of the phosphor.

Is Mercury the BEST Element to Function in CFLs?

Mercury in CFLs has been a topic of controversy these days, with the growing green movement. So, is mercury really the best or only element that can be used to make CFLs? Ed explains why mercury is indeed important to CFL production, despite the controversy.

He says that it seems that mother nature has chosen mercury to be the ideal element for this type of lamp (CFLs). Vapor pressure in the lamps, at the right temperature, is perfect with mercury. He says using a different element, such as cadmium, would not work out for the best. In order to get the correct vapor pressure at the same level (as with mercury), it would take much longer for the light to turn on. This, coupled with the fact that the bulb would have to be a much hotter temperature and add the risk or burning anyone who touched it.

The option of combining mercury with cadmium, to lower mercury amounts, would also not be useful – Ed points out that cadmium is also a banned element.

Based on Ed’s knowledge, mercury really is the best element possible as an option at this time. The environmental impact amount of mercury that is needed in fluorescent bulbs is still less harmful to the environment than the production of incandescent bulbs. The greatest source of mercury in our today air comes from burning fossil fuels such as coal, the most common fuel used in the U.S. to produce electricity. Since CFLs use 75% less energy than incandescent bulbs, they are dramatically cutting down on the amount of CO2 released into the environment.

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Ed Hammer found that he was competing against himself when he was working with different lighting. He had the HID lamps which had a life of 20,000-24,000 hours and then there were fluorescent lights with a life of 10,000 hours. He decided that he needed to get the fluorescent lights up to a life of 20,000 hours to be competing with high pressure mercury.

The first step taken was in changing the electrode. He used an optimized overwind on the filament and extended the length of the filament. This created the opportunity to put more of the emission mix on the filaments as they were longer. The ratio held up to increase the life of the bulbs significantly. Normally 4mg of mix were used making the life 10,000 hours, so when 8mg of mix were used the life did increase to 20,000 hours. He said even an increase of 50% would have been nice, but he got it all the way to a 100% increase!

He then designed a stick cathode that could hold these 8mg of mix. From here, the life of the lamps went up to 20,000 hours. This was the birth of the fluorescent lamp with a life of of 20,000 hours in the U.S.! This same type is used today, but has been improved with electronic ballasts. These help to cut down on the sputtering of the filaments, and the life of the bulb can be extended even beyond 20,000 hours.

The emission mix on the filaments that is discussed is a triple carbonate ( made of barium, calcium, strontium carbonate). This is used in virtually all fluorescent lamps today. They are heated during the lamp creation process to turn to oxide, which enables them to emit electrons and function (CO2 breaks down). They must be heated in the process in order to emit the electrons. The electrons can then come out freely leading to: minimizes sputtering, longer life, cleaner ends, and better maintenance of the bulbs.

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