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Views: 0 Author: Site Editor Publish Time: 2021-06-10 Origin: Site
Nowadays, in optoelectronic engineering, improving light efficiency, saving energy and high reliability have become the common goals pursued by people. When we discuss and use LED light sources, we will think of the characteristics of long life, energy saving, and high brightness of LEDs. Although the LED light source has the above advantages, it is not as wonderful as people say. Only when it is equipped with a suitable and efficient LED power supply, a reasonable circuit design, a perfect anti-static method, and a correct installation process can the above advantages of the LED light source be fully utilized and utilized.
1. Understanding of LED’s lifespan
The service life of LEDs is generally considered to be 100,000 hours under ideal conditions. In fact, the light intensity will gradually attenuate with the passage of time, that is, the efficiency of converting electrical energy into light energy gradually decreases. The effective light intensity range that we can really use should be when it decays to more than 70% of the initial light intensity. Whether the life span can be defined as the time period during which the light efficiency is gradually reduced to 70%, there is no clear standard yet.
2. Energy saving and reliability of LED
LED is a current-manipulating element that directly converts electrical energy into light energy through the current flowing through it, so it is also called a photoelectric converter. LED is a current-manipulating element that directly converts electrical energy into light energy by flowing current, so it is also called a photoelectric converter. Due to there is no friction loss and mechanical loss, it is more efficient than ordinary light sources in terms of energy saving. However, the LED light source cannot directly use the grid voltage like a general light source. It must be equipped with a voltage conversion device to provide a voltage and current that meets its rated voltage and current before it can be used normally, that is, a dedicated LED power supply. Different LED power supplies have different performance and conversion efficiency. Therefore, choosing a suitable and efficient LED power supply can truly show the high efficiency characteristics of LED light sources. Because the low-efficiency LED power supply itself needs to consume a large amount of electric energy, the high-efficiency and energy-saving characteristics of the LED cannot be displayed at all in the process of using it with the LED. And the LED power supply must also be a high-reliability power supply to make the LED light source system have a long life.
3. Basic characteristics and precautions of LED
(1) Photoelectric characteristics:
The greater the current flowing through the LED within its current limit parameter range, the higher its luminous brightness. That is, the brightness of the LED is proportional to the current passing through the LED. However, green light, blue light, and white light will saturate under high current conditions, which not only greatly reduces the luminous efficiency, but also shortens the service life.
(2) Optical characteristics:
LEDs can be divided into red, orange, yellow, green, blue, purple, white and other colors according to their colors. According to the brightness, there are general bright, high bright, super bright and so on. The brightness of the same chip in different packaging methods is also different. According to human vision, it can be divided into visible light and invisible light. According to the number of luminous colors, it can be divided into various types such as single color, double color, colorful and so on. The purity of the color varies greatly in price, and the current pure white LED is extremely expensive. At the same time, the light-emitting angle is different, and the light effect is also different, so special attention should be paid when using it.
4. Temperature characteristics:
(1) The soldering temperature of the LED should be below 250°C, and the soldering time should be between 3~5S. Pay attention to avoiding the high temperature of the LED and damage to the chip.
(2) The brightness output of the LED is inversely proportional to the temperature. Temperature not only affects the brightness of the LED, but also affects its life. Minimize the heating of the circuit during use, and do certain heat dissipation treatment.
5. Anti-static characteristics:
Anti-static measures must be strengthened during the LED assembly process, because the operation process and the human body will generate static electricity, and the double-electrode LED is most likely to be reversed by static electricity, which will severely affect the service life of the LED or even make it completely scrapped. If the anti-static environment is not perfect, you can add an anti-static wrist strap to LED users, set up a good anti-static grounding system, ion fans and other equipment.
6. Classification and characteristics of power supply
According to the driving method, the power supply can be divided into two categories.
(1) Constant current:
(a) The output current of the constant current drive circuit is constant, but the output DC voltage varies within a certain range with the size of the load resistance. The smaller the load resistance, the lower the output voltage. The larger the load resistance, the output voltage is higher.
(b) The constant current circuit can bear the short-circuiting the load, but it is strictly forbidden to open the load completely.
(c) Constant current driving circuit is ideal for driving LED, but relatively speaking, the price is higher;
(d) Should pay attention to the maximum withstand current and voltage values, it limits the number of LEDs.
(2) Constant voltage:
(a) When the various parameters in the constant voltage circuit are determined, the output voltage is fixed, but the output current changes with the increase or decrease of the load.
(b) The constant voltage circuit can bear the load open circuit, but it is strictly forbidden to short-circuit the load completely.
