LED fence tube reliability solutions

First, the use of rails

LED lights are widely used in the overpass fence, river, roads, gardens, building construction contours, large advertising signs, pedestrian bridges, discos, bars, karaoke room and so on OK, to beautify the urban environment ideal for decoration. The length of rails generally decided according to user requirements.

Second, the parapet of the technical parameters

LED guardrail light monochrome, color, colorful, such as color, or circuit controlled by microcomputer, can achieve a gradual, transition, color flashing, random flashing, gradual turn, running the chase, set color changes and other colorful effects can be configured independently of the operating parameters for each pattern, edit automatic operation mode, select the specified pattern. Can control dozens to thousands of bright LED guardrail lamp off, automatic storage set parameters, reload the preset parameters and other functions. Generally within the rails of a number of LED stars are: 96 / 108 / 144. Currently the main form to D-shaped tube. Voltage: DC 12V/24V/36V and AC 220V.

Third, the parapet of the choice of components

1, light beads:

LED fence tube light bead is certainly the most important components, but also the highest value. LED Light bead manufacturers must use the regular products. In our experience, the choice of 12 microns or more chips, definitely stronger than the 9-micron chips, mainly lies in more heat to be good, bad and reliability in the light would much better, but the average user can not detect it . Chengdu electronics company engaged in building stable LED light bead production, in addition to the chip, other auxiliary materials are strictly selected companies, which can guarantee the quality of the production of optical beads, guardrail good quality from the source put off.

2, Power:

Power supply rails in two ways: 220V high-voltage and low voltage below 48V. 220V direct power supply is a dangerous and uneconomical manner, low-quality approach is to supply electricity after the content or step-down resistor. The first is security in this way there is a big problem; followed by power and power is too great damage to the electricity sector is strongly against it. We have encountered several instances, LED is indeed power, but power produced is amazing. Such as Sichuan Yibin need parapet of a bridge over one thousand meters, it was cheap after the installation of power supply, less than half an hour almost led to the collapse of the city power lines, power lines across the board for the Bureau of forced outage. Our technical staff were invited to the site to help analyze the causes and found that each use of a guardrail 2. 2μ capacitance, measured more than 38 watts of power consumption, and the original report of the LED's power up more than 7 watts out of 5 times even more. The most terrible thing is: the sudden increase on the line then a large number of capacitive load, so that loss of power lines form a self-excited oscillation with, fortunately, otherwise properly disposed of duty may be a big accident. Therefore, we strongly urge not to use the power supply rails capacitor step-down way. So what way is the best? After deduction of our theory and practical test, we believe that use 36V DC power supply is below the best way to recommend it, the best to the DC voltage switching power supply, taking into account cost and line losses by segmented approach to power. Of course, the transformer is also useful ways by changing the pressure to convert 220V AC 30V AC low pressure to use, less efficient in this way some, if not regulated can lead to injury beads of light, and with the shortage of resources non-ferrous metals are also more expensive, not development.

3, the control mode:

Rails is generally changing color lights lit and colorful forms. Colorful change the control method used a simple transistor or CD4060 CD4060 plus plus CD40174, timing with the grid frequency 50Hz.

SCM procedures we recommend ways to better, nothing to do with the grid. According to our experience in the production, adding 595 with microcontroller circuit connection with a serial form at least, low cost and flexible in use. At present our new miniature rails power the results were good, cost, reliability, electromagnetic compatibility and other issues are resolved well, each guardrail one can solve the power supply rails Always question form. Transmission line voltage is 220V, power supply efficiency.

Fourth, LED Hulan reliability issues need to be addressed


1, water

LED fence tube interface is typically cover sealed with hot melt glue or silicone, internal LED, circuit board are exposed, due to large temperature difference between day and night, cover the ends of the different thermal expansion and contraction with the housing, resulting in hot melt or silicone seal a gap, after the rain the rain infiltrated the interior, causing a short circuit and burning LED. To solve this problem, certain requirements for the internal circuitry and LED plastic irrigation treatment. Hot melt glue or silicone joint seal alone is certainly simple, but not the reliability of large-scale outdoor applications. Another is the electrical connection of the joint problem. Many manufacturers often choose to cheap plastic joints, or choose low-quality metal joints, short of testing and use of plastic deformation has not waterproof is no problem, but after the sun's radiation and diurnal temperature changes, seasons change, the plastic will be deformed, resulting in failure of waterproof apron, rain infiltrated the joint lead to electrical short circuit inside, especially in the charged state, the corrosion of wires are not charged state than several orders of magnitude higher. Poor metal joints compared to the price and qualified products many times worse.

2, UV

LED guardrail light rain mixed with the requirements of the outside will have housing, housing choice of materials is that many non-standard companies as a means of reducing costs and good quality products will be increased use of UV materials, such as GE, Bayer, etc. materials, and poor quality of the LED fence tube outlet a lot of material using a mixture of materials, not to mention anti-ultraviolet, where sunlight is relatively large, less than a month, housing becomes yellow, and thus the optical effect of variation , transmission rate greatly reduced.

3, anti-cracking caused by thermal expansion and contraction, and internal stress

This is a housing problem, if you choose the material with the outlet material, material stress is difficult to remove, resulting in housing easy to crack. Even better material selection, if the design, production process is unreasonable, will also have a lot of stress, experienced companies will choose to temperature protection in the injection to minimize stress, and many physical methods used to eliminate internal stress. LED fence tube generally work in the outdoors, the temperature difference, the thermal expansion and contraction is the main reason for cracking housing, the current solution is to use a better minimal coefficient of thermal expansion and contraction of materials to produce.

4, line loss

Many non-ferrous metal prices, the use of inferior materials and reduce the diameter of some manufacturers to cost-effective way, we all know, the general good will in the internal use of the manufacturer of more than 1mm2 wire, and wire material used is in line with national standard products .

If the wire size is not enough or too many impurities in the material, the resistance value is larger, the barrier in front of and behind the rails of pipe have a large voltage difference, to make the back of the LED can work, you need to increase the input voltage, This virtually increases the power consumption, a lot of energy is not used to drive the drive LED, but the waste of the wire and the constant current chip. If the design of products in general before and after the voltage exceeds 15%, the problem is very serious, because chips are a common constant current power requirements, high voltage power to a large, if too much power, heat dispersion is not out will lead to chip burned. This is why a lot of class with the LED fence tube is much more reason behind the damage front.

5, heat

This not only reflects the cost, more technology embodies the strength of an enterprise. General LED fence tube housing and the low seat is completely integrated, all plastic materials. When the LED arrangement is very close, in the equilibrium through heating, LED junction temperature is already high, will result in sharp reduction in the life of LED. LED fence tube strength of the company will certainly be hot designers in the design of parapets will cover the idea when the LED chip, the heat and constant heat transfer effectively to the atmosphere. Aluminum is a better base to use solutions, high thermal conductivity of aluminum, the ability to export the internal heat. Also in the design and we should try to close aluminum PCB base, preferably in injection molding with aluminum base to suppress the water in which there is no problem.

6, the choice of Potting

Potting qualified should have the following characteristics:

⑴, seal adhesion performance, to improve the adhesion properties of the product.

⑵, no corrosion of pipes and modified pc: some glue on the market, in the tube after use may change the molecular structure of pc, pc tube significantly reduced the hardness and resistance to external performance, easy to become brittle, crack, thereby reducing light rails life.

⑶, environmental non-toxic harmless. Exports of electronic products to meet current product trends increasingly stringent environmental requirements.

⑷, moderate viscosity. In the bonding process to prevent a flow phenomenon, thus affecting the sealing effect.

⑸, anti-aging performance, long-term use of the lamp itself will not change color or cause discoloration.

⑹, heat resistance and stability. Temperature to ensure product performance, can resolve the long cold weather in the north and south hot and humid environment to use when shedding problem.

⑺, have excellent thermal conductivity, light beads or able to heat conduction out on the circuit.