How are light bulbs made?
There are specialist machines for manufacturing LED bulbs. We will briefly explain the process:
The manufacture of a LED bulb starts with a substratum. The materials used vary from sapphire (for white and cold tones) to gallium arsenide (warm tones).
AlinGaP technology is used for warm tones. Its name comes from the material used in its manufacture: Aluminium, Indium, Gallium and Phosphorus. InGaN technology is used for cold colours including white: Indium, Gallium and Nitrogen. The substratum is covered with different materials to make it resistant and long lasting. This is how the two LED semiconductors are created. Efficiency and quality depend on this process.
This substratum is housed in a wafer that is covered with material. After this, the chips and their corresponding LEDs are distributed. Then the temperature and brightness of the individual LEDs is verified.
The LED then needs to be provided with a base, a dissipater and a diffuser, as well as covering the chips with silicone to protect them.
Finally, the LED bulbs are classified according to their characteristics.
How do they work?
A LED bulb is a semiconductor device with two elements:
A type P semi-conductor: this means that it contains positive charge carriers.
A type N semi-conductor: charged with electrons with negative charge.
This combination creates a diode, which, when an electric current passes through it makes the positively and negatively charged particles move in opposite directions. When the particles collide, they liberate energy in the form of photons. The quantity of photons liberated determines the frequency (or colour) of the light. This is why two types of technology are used with different materials in the semiconductors (AlinGap and InGaN) to establish the colour of the light.
After processing the materials in the chip, it is placed with access to the electric current and with a space to generate light in the desired direction.
How have light bulbs changed since they were invented?
From Edison's patent to the present day, the light bulb has undergone numerous changes. A classic light bulb consisted of a simple glass bulb with a tungsten filament in a vacuum in its interior (or an inert gas). Since 2021, The European Union (UE) has prohibited their manufacture and import, to priority to more sustainable options.
At the end of the 19th century experiments were made with fluorescent lighting. In 1926, the German inventor Edmund Germer and his team implemented improved techniques that made fluorescent bulbs efficient and easy to manufacture. The North American company General Electric obtained the patent and started to market fluorescent bulbs in 1938. The EU plans to prohibit their manufacture and import from 2023 onwards.
Halogens are a development of the classic light bulb. In the 1950s, American engineers were looking for solutions for lighting aircraft. They were subsequently used extensively. In the EU their manufacture and import has been prohibited since 2018.
When talking about LEDs, we should mention research by Henry Joseph Round in 1907 and Oleg Lósev in 1927, prior to the development of the first commercial prototype and undertaken by in 1962 by General Electric. This first LED was infrared light. A decade later, Jacques Pankove explored LED technology for low-voltage blue light. At the start of the 1980s, Isamu Akasaki, Hiroshi Amano and Shuji Nakamura developed the first totally blue LED and perfected it as we know it today. Since then, the technology has progressed to create LEDs that are more powerful, more efficient and with more perfected colours. Nowadays it is the lighting most used in the EU because of its characteristics, whilst other types of bulbs are falling into disuse.