1. The working environment of outdoor LED lamps that outdoor lighting designers must consider

    Due to the complicated working environment, LED outdoor lighting fixtures are affected by natural conditions such as temperature, ultraviolet rays, humidity, rain, rain, sand, and chemical gases. Over a long period of time, the problem of serious LED light degradation will occur. So in the end, outdoor lighting designers should consider the impact of these external environmental factors on LED outdoor lighting when designing.

    Second, outdoor LED lamps should pay attention to the selection of heat dissipation materials

    The housing and heat sink are designed as one body to solve the LED heating problem. This method is better. Generally, aluminum or aluminum alloy, copper or copper alloy, and other alloys with good thermal conductivity are used. Heat dissipation includes air convection heat dissipation, strong wind cooling heat dissipation and heat pipe heat dissipation. (Jet cooling is also similar to heat pipe heat dissipation, but the structure is more complicated.)

    The choice of heat dissipation method has a direct impact on the cost of lamps and lanterns, and should be considered comprehensively, and the best solution should be selected in conjunction with the design product.

    The material selection of the lampshade is also crucial. At present, transparent plexiglass and PC materials are used. The traditional lampshade is a transparent glass product. What kind of material is selected depends on the positioning of the designed product grade. In general, outdoor lamps The best lampshade is traditional glass products, it is the best choice for manufacturing long-life, high-end lamps. Lampshades made of transparent plastic, plexiglass and other materials are better for indoor lamps, but have a limited life when used outdoors, because outdoor sunlight, ultraviolet rays, sand, chemical gases, and temperature differences between day and night make the lampshade aging life shortened , Followed by pollution is not easy to clean and clean, so that the transparency of the lampshade is reduced to affect the light output.

    Third, the outdoor LED chip packaging technology

    At present, most domestic LED lamps (mainly street lamps) are assembled using multiple 1W LED strings and parallel connections. This method has higher thermal resistance than advanced packaging technology products, and it is not easy to produce high-quality lamps. Or use 30W, 50W or even larger modules to assemble to achieve the required power. These LED packaging materials are encapsulated with epoxy resin and silicone. The difference between the two is that epoxy resin encapsulation has poor temperature resistance and is prone to aging over time. Silicone encapsulation has better temperature resistance, so you should pay attention to the selection when using it.

    It is better to use multi-chip and heat sink as a whole package, or use aluminum substrate multi-chip package and then connect with the heat sink through phase change material or heat dissipation silicone grease. The thermal resistance of the product is higher than that of products assembled with LED devices. One to two less thermal resistance is more conducive to heat dissipation. For lamps using LED modules, the module substrate is generally a copper substrate, and the connection between it and the external radiator should use good phase change materials or good heat dissipation silicone grease to ensure that the heat on the copper substrate can be transferred to the external radiator in time Upwards, if the treatment is not good, it is easy to cause heat accumulation to cause the temperature of the module chip to rise too high, which affects the normal operation of the LED chip. The author believes that multi-chip packaging is suitable for manufacturing general lighting fixtures, and module packaging is suitable for manufacturing compact led lamps (such as headlights for automobile main lighting, etc.) where space is limited.

    4. Research on the design of outdoor LED lamp radiators. The radiator is a key part of the LED lamp. Its shape, volume, and heat dissipation surface area must be designed to achieve benefits. The radiator is too small, and the working temperature of the LED lamp is too high. It affects the luminous efficiency and life. If the heat sink is too large, the consumption of materials will increase the cost and weight of the product, and the competitiveness of the product will decrease. It is very important to design a proper LED lamp heat sink. The design of the radiator has the following parts:

    1. Clarify the power that the LED lamp needs to dissipate heat.

    2. Some parameters for designing the radiator: specific heat of the metal, thermal conductivity of the metal, thermal resistance of the chip, thermal resistance of the radiator, thermal resistance of the surrounding air, etc.

    3. Determine the type of dissipation, (natural convection heat dissipation, strong wind cooling, heat pipe heat dissipation, and other heat dissipation methods.) From the cost comparison: natural convection heat dissipation cost is the lowest, strong wind cooling is moderate, heat pipe heat dissipation cost is higher, jet cooling The highest cost.

    4. Determine the maximum working temperature of the LED lamp (ambient temperature plus the allowable temperature rise of the lamp),

    5. Calculate the volume and heat dissipation area of the radiator. And determine the shape of the radiator.

    6. Combine the radiator and the LED lamp into a complete lamp, and work for more than eight hours with power on. Check the temperature of the lamp at a room temperature of 39 ℃ --40 ℃ to see if it meets the heat dissipation requirements to verify whether the calculation is correct. If the conditions of use are met, the parameters must be recalculated and adjusted.

    7. The seal between the radiator and the lampshade should be waterproof and dustproof. An anti-aging rubber pad or silicone rubber pad should be placed between the lampshade and the radiator. Fasten it with stainless steel bolts to ensure that the seal is waterproof and dustproof. Points to note, and then refer to the latest outdoor lighting technical specifications issued by our country, and urban road lighting design standards, this is the most basic knowledge that outdoor lighting designers must have.