The development of electric lights

The earliest practical electric lamp was an incandescent lamp, but before the birth of the incandescent lamp, the British Humphrey David used 2000 batteries and two carbon rods to make an arc lamp, but this arc lamp was too bright and produced too much heat. It's too much and not durable, and it can't be used in general places.

In 1854, Henry Gobert, a German watchmaker who immigrated to the United States, used a carbonized bamboo wire placed in a vacuum glass bottle to make the first practical electric lamp, which lasted for 400 hours, but he did not make it in time. apply for patent.

In 1860, the Englishman Joseph Swan also made a carbon filament electric lamp, but he failed to obtain a good vacuum environment to keep the carbon filament working for a long time.

It was not until 1878 that the British vacuum technology developed to a desirable level, that he invented a light bulb that was energized with carbon wire under vacuum, and obtained a British patent. Swann’s own house was the first private house to be lit by electricity in the UK.

In 1874, two electrical technicians in Canada applied for a patent for an electric light: nitrogen was filled under a glass bulb to emit light with an energized carbon rod. However, they did not have enough financial resources to continue to perfect the invention, so they sold the patent in 1875. To Edison. After purchasing the patent, Edison tried to improve the filament, and finally produced a carbonized bamboo filament lamp in 1880 that could last for 1,200 hours.

However, the US Patent Office ruled that Edison's invention of carbon filament incandescent lamp was left behind and the patent was invalid. After years of lawsuits, Henry Goebbels won the patent, and Edison finally bought the patent from Goebbels' impoverished widow. In the UK, Swan sued Edison for patent infringement. They later settled outside the court and established a joint company in the UK in 1883. Swan later sold his equity and patents to Edison.

At the beginning of the 20th century, the carbonized filament was replaced by a tungsten filament, and the tungsten filament incandescent lamp is still in use today.

In 1938, the fluorescent lamp was born. White LED lights were born in 1998.

type

1. Incandescent lamp

Modern incandescent light bulbs have coiled tungsten filaments and were commercialized in the 1920s, and were developed from the carbon filament lamps introduced around 1880.

Less than 3% of the input energy is converted into usable light. Almost all the input energy will eventually become heat. In a warm climate, this heat must be discharged from the building through ventilation or air conditioning, which usually leads to more energy consumption. In cold climates that require heating and lighting during cold and dark winters, the by-product of heat has a certain value. Due to the low energy efficiency of incandescent bulbs, many countries are phasing out incandescent bulbs.

In addition to light bulbs for general lighting, there is a very wide range, including low-voltage, low-power types that are commonly used as equipment components, but are now mainly replaced by LEDs.

2. Halogen lamp

It is usually much smaller than standard incandescent lamps, because for successful operation, the bulb temperature is usually required to exceed 200 °C. For this reason, most have a fused silica (quartz) or aluminosilicate glass bulb. This is usually sealed in an additional layer of glass. The outer glass is a safety precaution that reduces ultraviolet radiation and contains hot glass shards when the inner casing explodes during operation.

Due to the accumulation of excessive heat in the contaminated area, the oily residue of fingerprints may cause the hot quartz shell to crack. The risk of burns or fires of bare bulbs is also greater, leading to prohibition of use in some places unless they are enclosed by lamps.

3. Fluorescent lights

It consists of a glass tube that contains mercury vapor or argon at low pressure. The current flowing through the tube causes the gas to release ultraviolet energy. The inside of the tube is coated with phosphor, which emits visible light when irradiated by ultraviolet photons. Their efficiency is much higher than that of incandescent lamps. For the same amount of light produced, they usually use about one-quarter to one-third the power of incandescent lamps.

The efficiency of a typical light-efficiency fluorescent lighting system is 50-100 lumens per watt, which is several times that of incandescent bulbs with comparable light output. Fluorescent lamps are more expensive than incandescent lamps because they require ballasts to regulate the current through the lamps, but lower energy costs usually offset higher initial costs.

4. LED

Solid-state light-emitting diodes (LEDs) are popular as indicator lights in consumer electronics and professional audio equipment since the 1970s. In the 2000s, efficacy and output have risen to the point where LEDs are now used in lighting applications (such as car headlights and brake lights), flashlights and bicycle lights, and decorative applications (such as holiday lighting).

LED indicators are known for their extremely long life span, up to 100,000 hours, but the operation of lighting LEDs is much less conservative and therefore has a shorter lifespan.

LED technology is useful to lighting designers because it has low power consumption, low heat, instant on/off control, and in the case of monochromatic LEDs, color continuity and relatively low manufacturing cost. The life of the LED largely depends on the temperature of the diode.