Lighting plays an important role in human life. It can be basic, accent, decorative. Various light sources are used to create the backlight. The most modern, reliable and high-quality devices are LED lamps. They have many advantages over classic light sources. However, the design of an LED light bulb is more complicated.
Principle of operation
The basis of an LED is a semiconductor crystal, consisting of two materials with different conductivity.
The principle of operation of an LED lamp is as follows: when an electric current is applied, particles are transferred from one semiconductor to another, accompanied by the creation of a particle of light - a photon. Both semiconductors can only pass current in one direction, so polarity is important when connecting. During the supply of current, other processes also take place. Part of the energy is spent on generating heat.
LEDs are made of different materials, so their spectrum, flux intensity, brightness also differ. Currently, light emitting diodes cover almost the entire radiation range.
LEDs are used in a variety of areas: to create lighting in the home, in production, in office buildings. With their help, advertising, artistic and architectural lighting is made. LEDs can be found in street lamps.
Benefits of LED bulbs
The safety of LEDs lies in the absence of harmful components in them. There are no mercury vapors and a mixture of inert gases in the flask, so they do not require special disposal conditions. Also, the LEDs are made in a durable high-quality case. The devices have a low ripple factor, so they are safe for human health.
A wide range of LED bulbs can be found on sale. They differ in their characteristics, size, color temperature, design features. LED lamps are made in different shapes - a candle, a cylinder, a tube and others.
The disadvantage that limits the widespread use of LED devices is the high cost.
LED sources device
The overall design of the lamps is identical, there may be slight differences. They are more complicated from a technical point of view than incandescent bulbs. To find out what a light bulb is made of, you need to disassemble it, while in a classic light source with a filament, you can view the inside through a glass bulb.
What the LED lamp consists of:
- Led. One or more LEDs are installed in the lamp. They differ in power, glow color, size.The number of diodes in the matrix can be different, calculated in production to ensure the optimal light level. Diodes are soldered to an aluminum or textolite board of various sizes and shapes. The groups are connected to each other in series.
- Driver. It is used to convert the mains voltage to the value required for the LEDs to work. Driver circuits are different, most often transformer ones are used. By design, open and closed are distinguished, which are installed directly into the lamp body. Cheap Chinese products often contain low-quality drivers that are ineffective and can be harmful to health.
- Base / plinth. LED bulbs have come to replace incandescent bulbs, so they should be installed in the same way. Devices with standard E27 and E14 bases are manufactured.
- Housing. The flask is made of plastic or glass. Complete tightness is not required, since there are no harmful mercury vapors and gases in the composition.
- Radiator. Since a certain amount of heat is generated during operation, it must be removed so that there is no overheating. The aluminum plate reduces the negative effects of temperature, but this may not be enough. Therefore, expensive high-quality light bulbs are additionally equipped with radiators.
The range of products with E14 and E27 base can be divided into three categories - branded, low quality and filament.
Branded products
The device of an LED lamp made by a well-known company necessarily includes:
- Hemispherical diffuser. Can be made of plastic or glass.
- Aluminum PCB with heat-conducting paste.
- A set of chips.
- Driver. Consists of a pulse transformer, microcircuits, polar capacitors, planar elements. It is also a connector between the base / plinth and the radiator.
- Plinth base made of polyethylene terephthalate.
- Plinth with a thread of the required diameter, made of nickel-plated brass.
A high-quality device must have a radiator. It is voluminous and painted with a white polymer. Increases the weight and dimensions of the light bulb, but is an essential element for stable operation.
Low quality products
Unknown devices are usually of low cost. This is due to the use of low-quality materials and the lack of important parts - a heatsink and a driver. Instead of a driver, a conventional power supply is used, located next to the LEDs. The role of the radiator is played by the housing, in which holes are made. This method is ineffective, so cheap bulbs quickly fail.
The board is attached to the case with a special latch. The base and the board are connected by soldering. Such a connection cannot provide high reliability and long-term operation of the LEDs.
Filament devices
Externally, a filament light bulb looks like an incandescent light bulb. Its important distinctive feature is that no additional heat removal is required. This LED light bulb consists of a filament and a bulb.
Powered by LED filaments. Their number is selected depending on the power of the lamp. The LEDs are housed on a thin glass rod - this design is called a filament. A phosphor is applied along the entire length, so the lamp is yellow. Heat is removed through a flask with a mixture of gases inside.
The disadvantages of a filament lamp include a high ripple factor. Frequent blinking negatively affects the eyesight and psyche of a person, therefore, work is underway to modernize the lamp design. A high quality driver should fit into a plastic ring-shaped insert between the bulb and base.
Assembly methods
LED bulbs can be divided into several categories based on how they are assembled:
- Dip (dual inline package). This is the oldest and simplest design.It is a light-emitting diode located in a protective cylindrical case with two or more leads. They shine brightly, differ in a wide color gamut and low heating. There are one-color and multi-colored.
Piranha LEDs - Piranha. These devices have a high luminous flux. They are rectangular with 4 leads. Compared to the previous ones, the piranha is firmly installed on the board. Has a lead backing that increases thermal conductivity. Works over a wide temperature range.
- SMD. These are LEDs with a power of 0.01 - 0.2 W, characterized by the presence of several crystals on one ceramic substrate. The body is covered with a phosphor. The disadvantages include the impossibility of repair. If at least one LED in the group breaks, the entire board will have to be replaced.
- COB. One of the most reliable diode manufacturing technologies. The semiconductor crystal is mounted on a board without a case and substrate and is covered with a phosphor. They are characterized by high power and small glow area.
The most common technology is COB.
Recommendations for checking the lamp upon purchase
When buying a lighting product, it should be visually inspected in the store. The case must be free of scratches and dents. You need to make sure you have a radiator. It can be monolithic or typesetting. The dimensions depend on the power of the lamp - the higher it is, the larger the radiator.
The base is also checked. It must be free of mechanical defects and backlash. If possible, you need to check the operation of the lamp by connecting to the mains. You need to look at the light through the phone camera to make sure there are no pulsations. If flickering is noticeable, the lamp is of poor quality, it is not recommended to buy it.
Before making a choice, you should carefully study the technical characteristics: how many volts are the LEDs in the lamp, color temperature, ripple coefficient.
