This blog post explores how lighting technology has advanced to become smarter and more efficient, from incandescent bulbs to fluorescent lights, LEDs, and smart lighting.
Lighting fixtures that use electrical energy have continuously improved since the invention of the incandescent bulb, focusing on increasing luminous efficiency and extending the lifespan of the fixtures. Luminous efficiency refers to the ratio of electrical power consumed that is converted into light. Here, light refers to visible light, a type of electromagnetic wave located between infrared and ultraviolet light. Modern lighting fixtures are developing in a more efficient and environmentally friendly direction, with various technological innovations taking place.
The incandescent bulb has a simple structure: a filament placed inside a rounded glass bulb filled with an inert gas. When voltage is applied to the filament, the heated filament emits some of its energy in the form of electromagnetic waves. The wavelength of these electromagnetic waves forms a continuous spectrum, with light constituting about 10% and the remainder being infrared radiation in the form of heat. Most of the power supplied to the bulb is emitted as heat, resulting in very low luminous efficiency. Furthermore, the filament is heated to high temperatures, making it prone to breaking and leading to a short bulb lifespan. Increasing the voltage applied to the bulb raises the filament temperature, increasing the proportion of light emitted but shortening the lifespan. Due to these issues, incandescent bulbs are gradually being replaced by other high-efficiency lighting devices.
Fluorescent lamps consist of a cylindrical glass tube containing mercury and an inert gas, with filaments attached at both ends. When thermoelectrons emitted from the filament collide with mercury particles, ultraviolet light is generated. This ultraviolet light strikes the fluorescent material coated on the inside of the tube, converting it into visible light. The color of this light varies depending on the type of fluorescent material, and the conversion efficiency of ultraviolet to visible light also differs, affecting the lamp’s overall luminous efficiency. Since fluorescent lamps do not derive light directly from the filament, they can operate at lower heating temperatures. This allows them to produce the same brightness as incandescent bulbs while consuming about 30% less power. They also emit less infrared radiation than incandescent bulbs and have a lifespan approximately 5 to 6 times longer. However, fluorescent lamps also contain mercury, posing environmental concerns and safety issues during disposal.
Light-emitting diodes (LEDs) are made by joining two types of semiconductors: p-type and n-type. When voltage is applied, a constant voltage difference occurs between the two semiconductors. At this point, electrons moving between them emit light equal to the energy of this voltage difference. The required voltage and the amount of emitted energy vary depending on the compounds forming the two joined semiconductors. The wavelength of the emitted light is determined by this energy level, causing the light from the LED to appear as a single color. LED lighting is highly popular due to its low energy consumption, long lifespan, and ability to provide light in a wide variety of colors.
To use LEDs as light-emitting elements for illumination, they must be capable of emitting light across the entire visible spectrum. Therefore, a fluorescent material is applied to the light-emitting body that produces monochromatic light, enabling light emission similar to fluorescent lamps. However, since LEDs lack a heating element like a filament, they have a longer lifespan and lower energy loss compared to fluorescent lamps. Due to advancements in LED technology, they have now become the primary lighting fixtures replacing incandescent bulbs and fluorescent lamps, and are used in various applications.
The evolution of lighting fixtures using electrical energy continues, and recently, smart lighting systems have emerged, further enhancing the efficiency and convenience of lighting fixtures. Smart lighting utilizes IoT technology to allow users to control lighting remotely and maximizes energy savings through automated lighting adjustment functions. These technological advancements not only increase the efficiency of lighting fixtures but also significantly contribute to improving the quality of life for users.
