Compared with traditional light sources, LED lighting products are based on semiconductor solid-state lighting (SSL). Many parameters of LED lighting products are different from other light sources, and they need to be correctly and correctly controlled to be applied well.
First, light efficiency and luminous flux
The luminous efficiency and luminous flux of traditional light sources do not change much. For example, in fluorescent lamps, if the power of the light source is determined, the luminous efficacy and lumens will not change much, and the LED light source will be different.
For example, the light flux of the lamp in the 5730 package is 50 lumens, when the current is given 150mA.
Vf=3.0-3.2v, the power of the LED is 0.45-0.48 watts, and the luminous efficiency is 111.11-104.17 lm/w.
Vf=3.3-3.5v, the power of the LED is 0.495-0.525 watts, and the luminous efficiency is 101.01-95.24 lm/w.
It can be seen that under the same driving current, the luminous efficiency of the lamp bead is greatly deviated due to the different junction voltage of the LED, and the high lumen does not mean high luminous efficiency. For LED lighting products, high light efficiency is the main indicator. The relationship between driving current and light efficiency is shown in the figure:
It can be seen from the figure that the luminous efficiency of the LED light source product is a controllable index. By controlling the driving current, not only the luminous efficiency can be controlled, but also the luminous flux and the heat dissipation index of the lamp can be controlled. (Note: The part of the graph where the curve is not smooth is caused by the change of luminous flux caused by the airflow disturbance affecting the heat balance during the test, and does not affect the trend direction)
Second, color temperature and Bronx curve
The color temperature of incandescent lamps and energy-saving lamps is consistent in batch products. Due to the manufacturing process characteristics of LEDs, the color temperature deviation of each batch of packaged products is very large, and the color temperature of LED light sources is expressed by correlated color temperature (CCT). Means that there is a problem of color space uniformity (Δuv), which is a disadvantage of LED as a light source;
The color temperature inconsistency has been plagued by manufacturers who are pursuing high-quality LED lighting products. The color temperature problem is also expressed as the same value of the color temperature value test, but the light color is different. This is called the same temperature, and the visual light color is the same but The color temperature values ​​tested are different. This is called the same color temperature. The lower the color temperature, the more severe the isothermal color and the same color temperature. This problem can be seen from the CIE1931 chromaticity diagram below.
If the 3MK QM and QP light color will be very different, this color difference can be distinguished by the human eye, and the QO and PO light color vision will be lower than the former. The accurate method is to determine the LED color by spectral analysis. Coordinates, according to the order of the set MacAdam ellipse, using the blending technique and controlling the Δuv range to ensure the color temperature consistency of the product, the qualified enterprise can determine the order color temperature range rule of the enterprise to avoid the same temperature difference. color;
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