The data detected by the single LED flood light on the aging board, and the data detected when the LED flood light is assembled into a luminaire, is definitely a bit different.
The size of this difference depends on the electrical parameters of the LED during operation and the design of the luminaire, as well as the environment in which the luminaire is used.
First, choose what kind of LED white light.
This is very important, the quality of LED white light can be said to be a very important factor. To give some examples, the same LED 14mil white light segment chip is used as the representative. The LED white light with the epoxy resin and the white glue and the encapsulation glue is used to illuminate the LED white light in a single environment. After 1000 hours, the attenuation data is 70% light decay; if packaged with Class D low-resistance glue, the light decay is 45% in the same aging environment; if the C-type low-resistance glue is packaged, in the same aging environment , the light decay of 12 hours is 12%; if the B-type low-resistance glue is encapsulated, in the same aging environment, the light decay of thousands of hours is -3%; if the low-grade glue of type A, under the same aging environment, thousands of hours of light Decay to -6%.
Why are different packaging processes leading to big differences?
One of the main reasons is that LED chips are afraid of heat. Occasionally, the heat is more than one hundred degrees in a short period of time. It doesn't matter. I am afraid that if I am exposed to high temperature for a long time, it will be a great damage to the LED chip.
Generally speaking, the thermal conductivity of ordinary epoxy resin is very small. Therefore, when the LED chip is lighted, the LED chip emits heat, while the ordinary epoxy resin has limited thermal conductivity, so when you are from the LED white light When the external temperature of the LED holder is measured at 45 degrees, the center temperature of the chip in the white LED may exceed 80 degrees. The temperature node of the LED is actually 80 degrees. Then, when the LED chip works in the temperature of the junction temperature, it is very tormented, which accelerates the aging of the LED white light.
When the LED chip is working, the center temperature produces a high temperature of 100 degrees, and it can immediately release heat through the bracket pin 98%, thereby reducing the damage of heat. Therefore, when the LED white light bracket temperature is 60 degrees, its chip center temperature may be only 61 degrees.
It can be seen from the above data that the LED white light of the packaging process is selected to directly determine the light decay of the LED lamp.
Second, the LED lamp bead works at ambient temperature.
According to the data of the aging of a single LED white light, if only one LED white light is on, and the ambient temperature is 30 degrees, then the stand temperature of the single LED white light will not work. More than 45 degrees. At this time, the life of this LED will be ideal.
If there are 100 LED white lights that work at the same time, the interval between them is only 11.4mm, then the bracket white temperature of the LED white light around the stack may not exceed 45 degrees, but in the middle of the stack Those LED white lights are likely to reach a high temperature of 65 degrees. At this time, the LED lamp bead is a test. Then, those LED white lights gathered in the middle, in theory, the light decay will be faster, and the LED white light around the lamp pile will slow down.
However, if the LED beads are separated by more than 25mm, then the heat that they disperse from each other will not accumulate. At this time, the temperature of each LED white light bracket should be less than 50 degrees, which is more conducive to the normal operation of the LED.
If the LED working environment is in a cold place, the average temperature of the whole year may be only about 15 degrees, or less, then for LEDs, the life is longer.
Or, when the LED is working, there is a small fan blowing next to it, which helps it to dissipate heat. This is also very helpful for the life of the LED.
Anyway, everyone should know that LED is afraid of heat, the higher the temperature, the shorter the life of the LED, the lower the temperature, the longer the LED life. The ideal operating temperature of the LED is of course between minus 5 and zero. But this is basically impossible.
Therefore, after we understand the ideal working parameters of the LED chip, we will strengthen the function of heat conduction and heat dissipation when designing the lamp as much as possible. Anyway, the lower the temperature, the longer the LED life.
Again, the working electrical parameters of the LED lamp bead are designed.
According to the experimental results, the lower the driving current of the LED white light, the smaller the heat emitted, of course, the smaller the brightness. According to the survey, LED flood lighting circuit design, LED drive current is generally only 5-10mA; the number of lamps used in the lamp has a large number of products, such as more than 500, or more, the drive current is generally only 10-15mA However, the driving current of the general popular LED application lighting is only 15-18 mA, and few people design the current to 20 mA or more.
The experimental results also show that under the driving current of 14 mA, and the cover is airtight, the air temperature inside reaches 71 degrees, the low-fat product, the light decay of zero hours is zero, and the light decay of 2000 hours is 3%. This shows that this low-reduction LED white light has reached its maximum level in such an environment, and then it is a kind of damage to it.
Because the aging board for aging does not have a heat dissipation function, the heat generated by the LED operation is basically unable to be conducted to the outside. This is proved experimentally. The air temperature inside the aging board has reached a high temperature of 101 degrees, and the surface temperature of the cover on the aging board is only 53 degrees, which is a few tens of degrees. This shows that the plastic cover designed has substantially no heat dissipation function.
However, in general luminaire design, the function of heat conduction and heat dissipation is taken into consideration. Therefore, in summary, the design of the working electrical parameters of the LED lights bead should be based on the actual situation. If the heat conduction and heat dissipation function of the lamp is very good, it is irrelevant to increase the driving current of the LED white lamp, because the LED lamp bead works. The heat can be exported to the outside in an instant, and there is no damage to the LED, which is the best care for the LED. On the contrary, if the heat dissipation function of the luminaire is so sloppy, it is better to design the circuit to be smaller and let it put less heat.
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