LED is a new type of semiconductor solid state light source. It is a granular light-emitting device that does not require a tungsten wire and a tube. LED light source has become the new favorite of the lighting industry due to its many advantages such as environmental protection, energy saving, long life and safety.
In some PN junctions of semiconductor materials, the injected minority carriers recombine with the majority carriers to release excess energy in the form of light, thereby directly converting electrical energy into light energy. The PN junction is added with a reverse voltage, and minority carriers are difficult to inject, so they do not emit light. Such a diode fabricated by the principle of injection electroluminescence is called a Light Emitting Diode, and is generally called an LED.
Like ordinary diodes, LEDs are still formed of PN structures and also have unidirectional conductivity. The LED operates in a forward-biased state and emits light when it is forward-conducting, so it is a semiconductor device that converts electrical energy into light energy.
LED cross section
What are the characteristics of LED light sources?
1) High luminous efficiency: The luminous efficiency of LED is about three times that of ordinary incandescent lamps.
2) Low power consumption: LED power utilization rate is as high as 80% or more.
3) High reliability and long service life: LED has no vulnerable parts such as glass and tungsten wire, can withstand high-strength mechanical shock and vibration, is not easy to be broken, and has a very low failure rate.
4) Good safety, belonging to green lighting source: LED has low calorific value, no heat radiation, can be safely touched; light color is soft, no glare, no mercury, sodium and other substances that may be harmful to health.
5) Environmental protection: LED is an all-solid illuminant, which is resistant to vibration, impact, and is not easily broken. The waste can be recycled without pollution.
6) Good monochromaticity and rich colors: LEDs have multiple colors, the light source is small in size, can be combined at will, and can control the luminous intensity and adjust the lighting method to achieve the perfect combination of light and art.
7) Short response time: LED response time is only 60ns, which is especially suitable for light sources of automotive lamps. Since the LED reacts quickly, it can work at high frequencies.
8) Plane illumination, strong directivity: the viewing angle of the LED light source is ≤180. . Be careful when designing and using.
When white light LED lamps compete with traditional lamps in the field of indoor lighting, the biggest problem is that the initial purchase cost is too high. At present, the LED lamps on the market can not reach the brightness of ordinary bulbs. The application of indoor lighting is mainly concentrated in the field of commercial lighting, and the decorative lighting is mainly based on background lighting and partial lighting.
With the development and gradual commissioning of white LED lighting fixtures with high power, high luminous efficiency and high color rendering, the illumination is continuously improved and the cost is continuously reduced. It is an inevitable development trend for LED indoor lighting to enter thousands of households. LED outdoor lighting has also developed rapidly in recent years, such as road and tunnel lighting, building exterior lighting, and various night landscape lighting projects.
What should you watch out for when using LEDs?
1) The polarity of the LED must not be reversed. Usually, the longer lead is the positive pole and the shorter lead is the negative pole.
2) The parameters in use shall not exceed the specified limit values. The forward current IF is allowed to exceed the limit operating current IM value, and as the ambient temperature increases, the operating current usage must be reduced. The temperature should not exceed 75 °C for long-term use.
3) The normal operating current of the LED is 20mA, and small fluctuations in voltage (such as 0.1V) will cause large fluctuations in current (l070~15%). Therefore, in the circuit design, different current limiting resistors should be configured according to the voltage drop of the LED to ensure that the LED is in optimal working condition. If the current is too large, the LED will shorten the life; if the current is too small, the required luminous intensity will not be achieved.
4) When the luminance of the light is substantially unchanged, the pulse voltage driving can reduce the power consumption.
5) A sharp rise in electrostatic voltage and current will cause damage to the LED. It is strictly forbidden to touch the two pins of the white LED with bare hands. Because the static electricity of the human body will damage the crystal layer of the LED, after a period of operation (such as lOh), the diode will be ineffective (not lit), and will be ineffective immediately.
6) When tinning the LED, the device for heating the tin and the soldering iron must be grounded to prevent electrostatic damage to the device. The antistatic wire is preferably made of bare copper wire with a diameter of 3 mm, and the terminal is reliably connected to the power ground.
7) Do not install the LED with the pin deformed.
8) Avoid high temperature operation above 80 °C under power-on conditions. If you have high temperature work, be sure to dissipate heat.
What are the characteristics of LED driver?
LED lamps are fundamentally different from traditional incandescent lamps in terms of structure and illumination. The LED lights are driven by a low voltage power supply, the safety lines can be standardized, and the lines can be arranged in any shape at any position. Therefore, in addition to meeting safety requirements, the LED driver circuit must have the following two basic functions: First, it should maintain constant current characteristics as much as possible, especially when the power supply voltage changes ±15%, it should still be able to maintain the output current in the earth. Change within 10% range. Second, the driver circuit should maintain its own low power consumption, so that the system efficiency of the LED can be kept at a high level.
What types of LED drive power? What are the characteristics?
LED has the advantages of low energy consumption and long life, so many special applications will use LED as its light source; however, because the
power supply required for LED is DC, low voltage, it was used to drive the power of tungsten or fluorescent lamps. Not suitable for direct driving LED lamps. In order to meet the requirements of different input voltages, different output currents and different LED numbers, various semiconductor device companies have developed various new LED switching power supplies.
What are the applications of LEDs in the field of indoor lighting?
1) Indoor commercial atmosphere lighting: LED light source energy-saving and environmental protection, no UV, has become the preferred light source for some merchants to display for certain special products.
2) Lighting for leisure and entertainment places: LED integrated light source is easy to control with full color, which can create static and dynamic lighting effects, and opens up new ideas for the design of space environment decoration in casinos, beauty salons and other places.
3) Lighting in professional places: Museums, art galleries and other places belong to special occasions with high requirements for lighting environment. LED is a cold light source, and the light does not contain ultraviolet light, which can fully meet the special requirements of lighting in museums and art galleries.
4) Stage lighting: changing the lighting of the studio to LED, the energy consumption of the studio in lighting is reduced, and the room temperature can be reduced to a more comfortable level.
5) Hotel, hotel lighting: hotel, hotel lighting using LED products, or in the lobby, or in the guest room, to bring a different feeling to customers, in addition to saving energy, but also full of luxury and warmth .
6) Conference room, multi-function hall lighting: intelligent control LED, adjustable illuminance, can adjust the lighting environment of conference room or multi-function hall according to the content of the meeting, serious or lively can be set freely, LED intelligent lighting can Meet the requirements of different conference themes for the light environment.
7) Living room and home theater lighting: The use of LED lighting color can create a warm, harmonious and romantic atmosphere, reflecting the comfortable and casual atmosphere. The application of LEDs explains another meaning for home lighting.
What should you pay attention to when installing LED indoor lighting?
1) The power supply voltage should be consistent with the voltage indicated by the luminaire. Pay special attention to whether the input power supply is DC or AC. The power supply line should be equipped with matching leakage and overload protection switches to ensure the reliability of the power supply.
2) When the LED lamp is installed indoors, the waterproof requirement is basically the same as that in the outdoor installation, and the waterproof measures of the product are also required to prevent the humid air and corrosive gas from entering the line. When installing, carefully check the parts that are likely to enter the water, especially the line joints.
3) LED lamps are equipped with male and female connectors. When the lamps are connected in series, first install the waterproof ring of the male and female connectors, then connect the male and female connectors, and make sure that the male and female connectors are inserted into the bottom and then force the locking nut. can.
4) After unpacking the product, carefully check the lamp housing for damage. If it is damaged, do not illuminate the LED lamp and take necessary repair or replacement measures.
5) For extendable LED luminaires, pay attention to the maximum number of extensions that can be extended.
Quantity, can not be installed and used in series, otherwise it will burn the controller or the lamp.
6) When installing the lamp, if it is not allowed to be punched in glass, etc., it must not be directly fixed by glue or the like. It must be fixed with screws after erecting the iron frame or aluminum alloy frame; the number of screws should not be reduced at will when the screw is fixed, and the installation should be It is firm and reliable, and cannot be fluttering, swinging and loosening. It must not be installed in a flammable or explosive environment, and ensure that the LED lamp has a certain heat dissipation space.
7) During the handling and construction of the luminaire, do not drop, throw, press or drag the lamp body. Do not pull or bend the extension joints to avoid loosening the seal line and causing poor sealing or internal core wire breakage.
How to make the electrical connection of the LED bulb?
1. Electrical connection of low-power bulbs The installation method of low-power LED bulbs is relatively simple. It is usually powered by a 12V DC power supply. It requires lighting projection or lighting to illuminate indoors (such as ceilings and closets), with a power cord and control. System (power) connection, a certain number of LED bulbs can be achieved.
LED bulb electrical connection method diagram
