The research on non-strobe, from the power level is the most intuitive, in fact, is about the "frequency" problem, UHF eyes and CCD probe will not feel, low frequency eyes and CCD probe will have intuitive feeling. The way to achieve strobe free is either to do UHF DC output, or to actually remove or reduce the amount of ripple in the DC.

In 2014, the LED lighting market has already formed a blowout trend. As the standard configuration of LED lamps for lighting, constant current drive power will be the most fierce competition market. After all, intelligence is not the focus of the current market competition, from the perspective of the traditional enterprise pattern, drive power manufacturers now or from the price, delivery, quality, after-sales and other aspects of the play of competitive advantages, and strive to obtain development......

Now we do not lack of understanding of the new technology, it is difficult to choose their own suppliers in front of a hundred flowers blooming product technology. Today let's discuss: strobo-free technology in the field of LED civil lighting application of basic knowledge.

1. What is strobe?

Strobe and strobe effect are two physical quantities which are mutually causal for the electric light source, the fluctuation depth of the light flux and the magnitude of the resulting harmful effect (called strobe effect). Strobe refers to the depth of fluctuations in the luminous flux of an electric source. The greater the fluctuation depth of light flux, the more serious the stalling.

The strobe ratio is equal to the difference between the maximum and minimum light outputs in a switching cycle divided by the sum of the maximum and minimum light outputs. The strobe index is equal to the amount of excess over the average light output in a switching period divided by the total light output.

The luminous flux fluctuation depth of electric light source is directly related to the technical scheme of electric light source.

2. How to test strobe?

The human eye is insensitive to flicker above 60Hz, and the output power frequency of LED constant-current power supply is generally 100Hz or above. When using CCD photographic imaging (mobile phone, video camera), because of the different sampling frequency, there will be water ripples. However, it depends on the preset frequency of the phone, camera, sensor, shutter speed, so this test method is not necessarily accurate, but it is a simple test method.

The traditional test method is: in the sunlight, rotate the black and white gyroscope, the pattern will form a stable ring, the color ring will not change with the rotation speed, rotation direction. Under the tested light, rotate the gyroscope between black and white, and observe the phenomenon: if the color of the pattern or the ring structure changes, it means that the light is stroboscopic, and the more obvious the change, the more severe the stroboscopic. With this method, the strobe depth cannot be accurately evaluated.

The most scientific test method is the use of Light Flickering Analyzer, the core of which is an ultra-fast photometer with a sampling frequency of 10kS/s (10,000 tests per second). Scan the luminescent curve (similar to oscilloscope), and calculate the scintillation index and other parameters, to get the depth of light fluctuation (light ripple coefficient).

3. What kind of strobe depth is accepted?

There is no stroboscopic requirement, which is targeted to the needs of the market. At present, there are clear technical requirements in the United States, but most markets do not have a unified standard to strictly require the strobe depth of light source. At present, some customers require the fluctuation depth to be less than 8%, some to be less than 5%, and some to be less than 1%.

4. How to achieve strobo-free technology?

LED lighting products are driven by AC-DC constant voltage or constant current power supply. The light source itself does not affect the stroboscopic characteristics. Whether the output light is strobe or not depends on the design of LED driver power supply.

It is worth noting that stroboscopic is not the basis for judging the merits, reliability and quality of LED drive power, it just makes the light quality of lighting products more healthy. Therefore, to realize the strobo-free LED lighting products, the fundamental lies in the design of LED driving power supply.

Under the current technical background, the technical approaches to achieve strobo-free are as follows:

Scheme 1: Passive PFC+ valley filling circuit

Scheme 2, using a two-stage scheme, active PFC correction + flyback converter

Scheme 3. BUCK circuit without PFC correction

Solution 4. Special IC for ripple removal (without stroboscopic) in series at DC end of LED power supply

Solution 5. LED power supply DC terminal series linear constant current circuit