Application of LED light source in landscape lighting

LED light source is generally called the fourth generation illumination source or green light source, which has the characteristics of high energy saving, environmental protection, long life, small size and many changes. The LED light source is a light source that uses a light emitting diode as an illuminant. LED lighting products are lighting fixtures that use LEDs as light sources.

1 Basic characteristics of LED and precautions during use

1. 1 Photoelectric characteristics

The greater the current that the LED flows through the LED over its current limit parameter, the higher its luminance. That is, the brightness of the LED is proportional to the current 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.

1. 2 optical characteristics

LEDs are available in red, orange, yellow, green, blue, purple, and white. According to the brightness, there are bright, bright, super bright, etc. The same kind of chip has different brightness in different packaging modes. According to human vision, it can be divided into visible light and invisible light. According to the color of the illuminating color, it can be divided into various types such as monochrome, two-color, and colorful. The purity of the colors is different, the prices vary greatly, and the current pure white LEDs are extremely expensive. At the same time, the light-emitting angles are different, and the light effects are different. Pay special attention when using them.

1. 3 common LED electrical performance parameters

1) LED forward voltage. Different color LEDs have different forward voltage drop values ​​under rated forward current conditions, red and yellow: 1. 8 V~ 2. 5 V, green and blue: 2. 7 V~ 4 Between 0 V. For LEDs of the same color, the forward voltage drop and light intensity are not exactly the same. 2) The rated operating current of the LED. LEDs have different current ratings. Normal LED currents are typically 20 mA, and high-power LED currents typically range from 40 mA or 350 mA. Specifically, it should be selected according to the current parameter values ​​provided by each package factory. In general, the LED has a reverse current of IR 10 A under the condition of a reverse voltage of VR = 5 V. 3) The power of the LED. The LED power is also different, with 70 mW, 100 mW, 1 W, 2 W, 3 W, 5 W, etc., so it is necessary to design a reasonable use of the circuit and configure the appropriate number of LEDs according to the selected LED. It fully meets the rating of the LED power supply.

1. 4 Temperature characteristics

1) The soldering temperature of the LED should be below 250, and the soldering time should be controlled between 3 s and 5 s. Care should be taken to avoid damage to the chip due to excessive LED temperature. 2) The brightness output of the LED is inversely proportional to the temperature. The temperature not only affects the brightness of the LED, but also affects its lifetime. Minimize circuit heating during use and do some heat dissipation.

1. 5 anti-static characteristics

Anti-static measures must be strengthened during LED assembly, because the operation process and the human body itself generate static electricity. For the two-electrode LED, it is most likely to be reversely broken by static electricity, which seriously affects the service life of the LED and even completely eliminates it. If the anti-static environment is not perfect, you can add an anti-static wrist strap to the LED user, set up a good anti-static grounding system, ion fan and other equipment. Due to these characteristics, LEDs are now widely used in a variety of indications, displays, decorations, backlights, general lighting and urban night scenes. The typical use of LEDs is display screens and indicator lights. The technology used for decorative purposes is also mature. It is widely used in signage and light sculptures. LEDs are gradually replacing traditional Mind-resistant lamps.

2 LED application in landscape lighting

1) Energy saving and environmental protection. a. High luminous efficiency: In terms of energy saving, after several decades of technical improvement, LED's luminous efficiency has been greatly improved. Moreover, its light has good monochromaticity and narrow spectrum, and it can directly emit colored visible light without filtering. At present, countries all over the world are stepping up research on LED light efficiency, and their luminous efficiency will be greatly improved in the near future. b. Low power consumption: LED single tube power 0. 03 W~ 0. 06 W, DC drive, single tube drive voltage 1. 5 V~ 3. 5 V, current 15 mA~ 18 mA, its electro-optical power conversion Close to 100%, fast response, high frequency operation. The energy conversion efficiency of LED light source is very high. The same lighting effect is more than 80% energy saving than traditional light source. The brightness of a 50 W energy-saving lamp can be equivalent to that of 300 W~400 W high-pressure sodium lamp, and the light life is increased by more than 10 times, while the electricity cost is To reduce by nearly 90%. The energy-saving effect is remarkable, which is undoubtedly of great significance to China, where energy is very tight. It has better environmental benefits, no ultraviolet and infrared rays in the spectrum, no heat, no radiation, little glare, and waste can be recycled, no pollution, no mercury, cold light source, safe touch, typical Green lighting source.

2) Long life. The service life of LED lamps can reach 5 to 10 years, which can greatly reduce the maintenance cost of lamps and avoid the pain of frequent lamp replacement. More than 10 times longer than traditional light sources. Under normal circumstances, the use of LEDs, the light fade can be reduced to 70% of the nominal life of 100,000 h, reducing the frequency of replacement and other maintenance work.

3) The light color is pure. Since typical LEDs have a narrow spectral range, they do not have the full spectrum like incandescent lamps. Therefore, LEDs can be arbitrarily combined in a variety of ways, especially for decoration and other aspects.

4) Moisture and vibration resistance. Since the exterior of the LED is mostly protected by epoxy resin, the sealing performance and impact resistance are good and are not easily damaged. It can be applied to underwater lighting.

5) Safe and reliable. The operating voltage of the LED unit is between 1.5 V and 5 V, and the working current is between 20 mA and 70 mA. Human contact is not dangerous. Lamp body epoxy resin package, strong resistance to mechanical shock and vibration, no harmful substances such as mercury and sodium, can be recycled; low calorific value, no heat radiation, cold light source, safe touch; precise control of light type and illumination angle The light color is soft and there is no glare. Built-in micro-processing system, which can control the intensity of illumination and adjust the illumination method to achieve the combination of light and art.

6) Convenient management. Compared with the monotonous lighting effect of traditional light sources, LED light source is a low-voltage microelectronic product, which successfully combines computer technology, network communication technology, image processing technology, embedded control technology, etc., so it is also a digital information product, which is a semiconductor optoelectronic device. #高新尖∃ Technology, with online programming, unlimited upgrades, flexible features, is pure high-tech technology. Due to the above characteristics, LED light sources can be controlled in a variety of ways, such as centralized control and decentralized control or adjustable control of points. By controlling current dimming, different light colors are combined to color, and a control circuit is added to achieve various dynamic changes. Its long life of more than 100,000 h is to reduce the maintenance workload of urban landscape lighting. Other advantages include low heat, miniaturization, and short response times.

3 LED lighting development

1) Break through the concept of traditional light bulbs and bulb-based lighting, and develop surface light sources. Incandescent light sources have been used for more than 100 years and become the traditional habit of people. However, the light bulbs are more concentrated. Too bright will produce a dazzling feeling. The light is not soft and the working surface is uneven. It is necessary to use special light distribution to overcome the above shortcomings. . The LED light source can be made into a two-dimensional surface light source and made into a light-emitting panel in the form of a backlight.

2) Break through the concept of counterfeiting sunlight and develop a combined lighting system for digitally gradable light. Whether the artificial light source must imitate the sunlight is a problem worth exploring. There is no sunlight at night, and the lighting can choose different light sources according to the needs of different people. LED color can effectively treat SAD (seasonal mood disorder) diseases; purple and blue light can promote the production of vitamins A and D, and then promote the absorption of calcium, blue light can go to yellow gallbladder; Indian medical scientist DP Chadiali uses 12 kinds Color light irradiation treats allergic reactions, immune system disorders, cardiovascular diseases, mental stress, depression and insomnia. Therefore, modern lighting is a digital color light combination lighting system that can be adjusted according to the physiological and psychological needs of different people.

3) Break through the concept of traditional street lamps and develop a humanized LED street lighting system. Due to the requirements of urban greening, many street lamps are illuminated on trees, and there is no effective use of light energy, resulting in great waste. On the branch road and the mixed road of people and vehicles, the street lamp can be placed in the middle of the road, suspended along the center line of the road, and the light energy can be used evenly and effectively. The poles on both sides are made into columnar illuminators, illuminating the low places and making scattered The light source can make full use of the advantages and advantages of the LED light source, and is more user-friendly.

4) Breaking through the concept of traditional object color, high-saturation chromatic lighting brings visual cognition to a whole new level. The reflectivity of the object to different spectra and the intensity of the light source determine the color and color of the object. The color purity of the traditional light source (except the laser) is not high, that is, the color saturation is not high. In the single-wavelength color light, more background light brightness (luminance) is mixed, that is, white light is superimposed, and the color of the color light is lowered. Saturation, object color is not so bright, using LED high-purity blue, green, red light to illuminate objects will have different effects.

5) Breaking through the concept of traditional lighting, lighting should be a system. The LED industry technology is constantly evolving, and research on the improvement of luminous efficiency is the mainstream of industrial technology. However, in order to effectively use light and color light, to transmit light to where it is needed, and to meet the visual and physiological needs of human beings, it is necessary to study the compatibility of spectral combinations of different frequencies with human visual cognition, and to study light sources, lamps, Light distribution to the human body and visual interaction, as a value chain system to study how people can more effectively, healthily and scientifically use the lighting system to see the surrounding things, add valuable new elements to the value chain, and propose to use The value of the market, to promote the market, expand market demand.