Analyze whether the blue light in the LED lamp hurts the eye

Blue light is harmful to the eye Blue light damage depends on the total dose of blue light received by the human eye, and the same color temperature LED lamps and energy-saving lamps are almost the same safety.

In-depth analysis of whether the blue light in the LED lamp hurts At the 2013 China (Shanghai) International Semiconductor Lighting Application Technology Forum held recently, the participating experts discussed the issue of Blu-ray security. According to Professor Tong Tongsheng, a professor of optoelectronics information engineering at Zhejiang University, the visible light consists of seven colors: red, orange, yellow, green, cyan, blue, and violet. The wavelengths between 435 and 500 nm correspond to blue and cyan. The scientific community generally refers to the 400-500 nm wavelength range as the "blue zone."

Associate Professor Zhang Shanduan, deputy director of the Institute of Electric Light Sources at Fudan University, pointed out: "The principle of white LEDs is that blue LED chips stimulate the conversion of yellow phosphors to form white light. Blu-ray damage refers to the 400-500 nm blue wavelength of light sources. If the brightness is too high, the eyes are long. Time-directed light sources can cause photochemical damage to the retina. The degree of blue light damage depends on the amount of blue light that the human eye has accumulated in the light."

"The current technology of LED lamps commonly used in the market 'blue chip + yellow phosphor', so that the content of blue light in the LED light is relatively high, but this does not mean that the LED light is more eye-breaking than other lamps." Zhang Shanduan said in their work In the comparison experiment, the safety of the same color temperature LED lamp and energy-saving lamp is almost the same.

Color temperature is the most common indicator of the spectral quality of a light source. The "warm light" color temperature is lower, and the "cold light" color temperature is relatively high. As the color temperature increases, the proportion of blue radiation increases and blue light increases. At the same time, the brightness also affects the proportion of blue light. In general, the same color temperature of fluorescent and LED lights, as long as the latter's brightness does not exceed the former 3 times, basically no harm. However, for individual LED lighting that is too bright, the proportion of blue light may exceed the safe value. Zhang Shanduan said that with the maturity of LED technology, manufacturers no longer need to increase the color temperature and power of the lamps to achieve high lumens, and objectively reduce the possibility of excessive blue light.

Sun Xinghuai, dean of the Shanghai Eye, Nose and Throat Hospital, said that Blu-ray is not unique to LED lights. Both mobile phones and computer screens are rich in blue light. The hospital has never received any cases of eye injuries due to the use of LED lights.

According to Yu Anqi, director of the National Electric Light Source Quality Supervision and Inspection Center (Shanghai), answering this question is like answering the question of whether the sun is safe. In general, the sun is safe; but if you look at the sun, it can cause eye burns.

The National Semiconductor Lighting Engineering R&D and Industry Alliance and the China Illuminating Society recently organized more than 10 well-known domestic experts to discuss the issue of whether “blue light is hurting the eyes” and formed a white paper titled “Ordinary Lighting LED and Blu-ray.” According to Prof. Zhou Taiming, the white paper writing group's expert representative, “The blue light irradiation of the white LED light source on the retina of human eyes is similar to traditional light sources such as fluorescent lamps and metal halide lamps, and will not cause harm to human eyes.”

How to use LED lamps do not look directly for a long time, the new mandatory standards are being formulated. "If you buy a qualified lamp and use it properly, LED lamps are no more dangerous than traditional lamps." Yu Anqi said that our country's national standard "lamps and In the light biosafety of the lamp system, a clear description of the hazards of blue light and the calculation method for quantification was made, and it was pointed out that there was no difference between LED lighting products and other light sources, and it was within the safety range specified by the limits of exposure radiography.

However, experts say that this standard is a "recommended standard" rather than a "compulsory standard."

Prof. Tong Shengsheng said that according to the intensity of blue light, international standards for photobiological safety related to blue light have been established, and various values ​​that may lead to blue light damage have been set. For example, a light source product that does not have a Blu-ray hazard is called a “zero product”; a product that has less blue light hazard and does not allow the eye to look directly at the light source for a long time is called “a type of product”; a light source that will have a greater blue light hazard It is called "second type product". Currently used as the basic zero-class and one-class LED lighting, if it is the second category it is mandatory to mark the "eyes can not stare at" label.

As the person in charge of the development of the international standard for the safety and performance of LED technology, Zeng Tongsheng stated that in Europe and America, lighting products including LED technology must meet the international standards issued by the International Commission on Illumination (IEC). However, the standard became a "recommendation standard" after it was introduced into the country, which led to worrying about the safety performance of some domestic LED products.

Zhai Tongsheng revealed that the new mandatory national lighting safety standard is under development and is expected to be introduced next year. At that time, consumers will see "Zero" or "One Class" signs when choosing lamps. For lamps with light sources larger than Class II, there will be a symbol to remind "The lamp cover must not be removed when cleaning", and "Not suitable for straightening. "Light source" and other warnings.

How to buy LED lamps is recommended to use lamps with plastic diffuser, for children to buy low color temperature lamps should be selected Zhang Shanduan said that they in the LED, incandescent, energy-saving lamps, halogen lamps and other light sources after experimental testing found that In the "blue light dose", the transparent LED light emitting surface is much higher than the incandescent light bulb and the energy-saving lamp. However, the blue light dose of the LED light with a plastic diffusion panel on the light emitting surface is very small, lower than the incandescent lamp and the energy-saving lamp. Therefore, when using LED lights for indoor lighting, it is recommended to use lamps with plastic diffusers.

Experts said that the so-called eye-protection lights on the market may not be able to really protect the eyes. Because the classification of light radiation safety of various types of lighting has not yet been incorporated into the safety production standards of products in China, the current “eye protection light” is only the marketing term created by the lighting manufacturers, and none of them has obtained the scientific certification of the relevant national quality supervision departments.

Sun Xinghuai pointed out that it is best to use only zero-grade products for groups with special requirements for light security, such as newly born babies, patients with a history of diabetes for more than 10 years, certain types of hypertensive patients, and those who are taking photosensitive drugs. .

Professor Zhou Taiming said that Blu-ray controls the human biological clock to some extent. Blue light stimulates the secretion of cortisol (cortisone) in our body and allows us to work vigorously. At night, it is not appropriate to use more cool blue light, preferably warm light.

Zhang Shanduan suggested that when purchasing LED table lamps for children, lamps with a low color temperature (about 2700 Kelvin) should be selected, which will have less impact on the secretion of melatonin in the human body and help the child to sleep; when purchasing indoor LED lighting, try to choose a diffusion cover. Or a diffuser, lamps that do not see the chip directly, and do not emit light at a concentrated point.