Reasons for dimming LED light bulbs

Posted by ff on December 4th, 2020

Guangli introduces the reasons for the dimming of LED light bulb.

1. The quality of LED products:

1. The LED chip used is of poor physique and the brightness decays quickly.

2. There are defects in the production process, and the heat dissipation of the LED chip cannot be well derived from the PIN pin, which causes the high temperature of the LED chip and the chip failure.

2. One or some LEDs are burnt out.

Many LED lights are grouped in parallel. For example, 60 LED lights are divided into 3 groups, and each group is 20 in series. When a certain LED in a group burns out, all the LEDs in the group are not bright, but the LED lights in other groups are still normal Light up, due to the lack of a certain group of LED lights, the entire LED lights will be significantly dimmed. The principle is similar to the figure below. The figure below shows a parallel connection of 4 LEDs as a group. Burning one group has almost no effect on the other groups.

It is best to disassemble the lampshade of the LED lamp and check if there is any LED lamp bead that is not bright. . In this case, you need to replace the LED, but most people will not have ready-made lighting LED lamp beads, and it is very troublesome to buy. The lamp beads are not very expensive, but the shipping fee is expensive! If you only burn one or two, you can use about 150Ω If a group of more than 20 LED lamp beads are connected in series, it can be directly short-circuited after a certain LED is burned, which has almost no effect.

3. The heat dissipation problem of the product causes,

There are bricks in the production process, and the LED chip heat dissipation is not good. It is derived from the PIN pin, which causes the LED chip temperature to be too high and the chip attenuation increases. LED lighting has been solving the heat dissipation problem since its birth. This is why the product heat dissipation components and shells are used The main original solid of the aluminum village. Solving the problem of soil heat dissipation is the most important way to improve the life of the LED and reduce the light decay, and the effect is the most obvious.

Fourth, the chip

The chip is the luminous body of the LED lamp, so when the chip is damaged, the brightness of the LED lamp will be weakened, which is what we call dimming, which will seriously cause the entire LED lamp to not light up. Minghong uses the original imported COB high-brightness chip to reduce the light decay from the source, and the light is uniform and comfortable, more transparent and bright, with a long service life and a three-year warranty.

Fifth, the capacitance of the capacitive resistance step-down circuit has deteriorated.

The capacitive resistance pressure circuit is composed of a capacitor and a resistor in parallel. The capacitive reactance of the capacitor Xc=1/2πfC, where π is a constant of about 3.14, f is the frequency of alternating current, the frequency of 220v alternating current is 50HZ, and C is the capacity of the capacitor. When the capacitance value of the capacitor becomes smaller, the capacitive reactance becomes larger, which causes the total impedance of the capacitive resistance circuit to become larger, and thus the voltage drop becomes larger, which causes the voltage of the rear-end LED to be lower, which makes the LED dim.

Summary: There are many reasons for the light decay of LED products, and the most critical one is the heat problem. Although many manufacturers do not pay special attention to the problem of heat dissipation in secondary products, the degree of light decay will be more important than those of secondary LED products under long-term use. The heat dissipation of LED products is higher. The thermal resistance of the LED chip itself, the influence of silver glue, the heat dissipation effect of the substrate, and the glue and gold wire are also related to light decay.