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Flashing in Lighting

Jul. 13, 2020
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Every family in today's life is equipped with LED lights. We should all notice that sometimes we will see the lights blink. What is going on? What is the reason for the blinking of the led light? Many people are more interested in this issue. Today, the indoor COB LED chip factory will talk about it for everyone. Let's learn together!

What is flashing

When it is strong enough, you all know the effect. The lamp will go out in a short time and turn on again. This used to be a problem with fluorescent tubes. At least I knew it was time to change the lights.

Blinking refers to the rapid and repeated changes in light intensity, making the light look unstable and broken. This effect is caused by changes in power supply voltage or power line voltage.

These changes may be caused by dimming or using high current welding machines. Usually, the voltage change is very small and will not cause any damage to the lamp. However, even small changes can cause flicker and affect people working in offices, schools, etc.

Can you see the flashing

It depends on the situation. The human eye can see flashing lights up to 50 to 60 times per second (50Hz-60Hz), and the most sensitive frequency range of the human eye is 10Hz to 25Hz. When the frequency is higher than 60 Hz, most people cannot detect flicker. Some people already know to see flashes up to 100 Hz.

In fact, the flashing frequency of fluorescent lamps using magnetic ballasts is around 100-120 Hz, which is not visible to most people. This is because it is powered by a ballast with a frequency of 50 Hz (60 Hz in the US), and the lamp flashes at a dual-frequency. When there is a problem with the fluorescent lamp or the ballast, the flicker frequency drops below 100 Hz (usually the ballast frequency), which can be seen by the human eye.

A flicker from 100Hz to 500Hz will produce a stroboscopic effect, which means that what you see is a series of still images. This light is used in discos, but can be very dangerous in other environments.

When the flicker reaches a frequency of about 2 kHz, we can no longer detect it.

Is it harmful to you?

People already know that flashing lights can cause headaches, eye strain, and fatigue. In some countries, there are laws that provide maximum flicker in certain environments. For example, in Russia, schools, offices, etc. have regulations.

Some countries are becoming aware of these health problems and have begun to regulate the maximum flicker of lamps.

Why does the LED blink?

The problem with LEDs is that they are very different from older lighting technologies.

In short, if the LED provides a constant current, it will not blink. But the current must be constant.

The most common cause of LED flicker is a bad LED driver. If the driver cannot provide constant current, the LED it powers will blink.

When the drive converts AC to DC, some ripples will be generated, which will cause the frequency to usually jump to twice (just like a fluorescent lamp). This means that the LED waveform will follow the driver waveform.

The flicker on the driver is called ripple. Basically it is a synonym for flashing.

Another reason for LED flashing is dimming. If the dimmer controls the LED at a frequency below 200 Hz, it will cause significant flicker. This is because some dimmers alternate the current provided by the LED.

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