Consumer Warning: So-called 'Eye-Caring' Desk Lamps May Be More Harmful to Eyes

Jiangsu Provincial Consumers Association organized a comparative test of 173 batches of reading and writing table lamps on May 16. The samples were purchased from physical malls and online stores (Tmall, JD.com and Suning.com). The test covered 5 technical indicators, namely power cord length, light shading, color temperature, color rendering index and photometric requirements.

The test results show that only 3 batches meet the requirements of the above five technical indicators, and 98% of the tested samples fail to meet the technical indicators; more than 80% of the table lamps have excessively high color temperature, which may affect visual health.

▼ Types and quantities of light sources for 173 batches of samples

Test background: The proportion of vision loss and myopia among primary and secondary school students in Jiangsu Province shows an increasing trend. In order to better provide consumption guidance for consumers, guide consumers to correctly choose table lamps for children's reading and writing, and protect the visual health of students, especially primary and secondary school students, the Jiangsu Provincial Consumers Association organized a comparative test of reading and writing table lamps in accordance with the duties conferred by the Law of the People's Republic of China on the Protection of Consumers' Rights and Interests.

More than 80% of table lamps tested have excessively high color temperature

The test results of 173 batches of samples this time show that only 38 batches have a power cord length reaching 1.8m, meaning more than 80% are unqualified; 84 batches of table lamps have central area illuminance that does not reach Class A (250lx), and the central area illuminance of 20 batches of table lamps does not even reach 100 lx, which is nearly 50% unqualified.

According to relevant standards, the color rendering index of the light source of reading and writing table lamps shall not be lower than 80. In this test, 71 batches of table lamps have unqualified color rendering index Ra. A too low color rendering index of the light source cannot correctly display the color of objects, and also has a great impact on comfort, easily causing visual fatigue.

In this color temperature test of table lamps, 4000K was taken as the reference standard, and only 30 batches of table lamps have a color temperature lower than 4000K, which means more than 80% of the table lamps have excessively high color temperature. In this comparative test, there are also 21 batches of table lamps with a color temperature exceeding 6500K, and there is even an LED table lamp with a color temperature as high as 11643K.

The color characteristics of light emitted by a light source are determined by correlated color temperature and color rendering index. According to relevant standards, the correlated color temperature of table lamps for reading and writing should not exceed 4000K. This is mainly considering the impact of blue light on the circadian rhythm. Blue light has a wavelength of around 450nm, which is exactly related to the human body's circadian rhythm, and it has a strong ability to make the human body secrete melatonin inhibitors.

If the color temperature of the light source is too high, such as exceeding 5500K, a large amount of the spectral energy emitted by the light source is in the 460nm region, which exactly matches the waveform of the circadian rhythm curve. This will affect the body's normal immune mechanism, make people feel excited and difficult to fall asleep. In the long run, it will also affect the body's immune mechanism. Especially for primary and secondary school students in the critical period of growth and development, they are more vulnerable to visual hazards. Therefore, teenagers should not use high-color-temperature LED table lamps at night.

Common consumption misconceptions among the public

Many products on the market advertise themselves as "eye-protecting table lamps", which easily leads consumers to mistake the "product name" for "function". In fact, "eye-protecting lamp" is just a common name. The state has not issued specific standards for reading and writing table lamps with eye-protecting functions, and the relationship between eye protection and table lamp performance has not been strictly demonstrated.

Currently, eye-protecting table lamps on the market have another major selling point - "no flicker". The basic working principle of most eye-protecting lamps on the market is to increase the oscillation frequency of ordinary fluorescent lamps, from low-frequency flicker to high-frequency flicker, so that the naked eye cannot distinguish the flicker. However, long-term close use of high-frequency lamps will instead affect health.

Many consumers take "high brightness" as the standard when choosing table lamps. They do not know that while the lamp greatly increases the illuminance, the brightness of harmful reflection is also greatly increased. This will cause damage to the cornea, inhibit the function of retinal photoreceptor cells, and make people feel visual fatigue.

In addition, as an emerging lighting product, LED has won the favor of consumers with its high light efficiency and long service life, giving people the illusion that LED is high-end and high-quality. In fact, since most LED lamps use white LED, they are more prone to direct glare. If there are no anti-glare measures such as light exit angle design, grilles and lenses, it will cause a dazzling feeling, which is not conducive to reading.

How to correctly select healthy light source products

Yiguang Technology reminds everyone that when purchasing, in addition to buying through formal channels and checking the relevant certification and marks of table lamp products, you should also pay attention to important performance parameters such as the color temperature, color rendering index, uniformity of the light source, and whether there is glare.

Among existing light sources, the color temperature of candlelight is about 2000K, that of incandescent lamps is 2700-3000K, that of morning sunlight is about 4400K, and that of noon sunlight rises to 5600K. It is ideal for people to use light in different time periods in line with the laws of nature. However, current LED lamps on the market generally have high color temperature, which will interfere with the human body's biological clock. Long-term use will affect sleep, cause biological clock disorder, and thus reduce people's immunity. At present, OLED is a relatively ideal light source, with a color temperature of 3000-4000K. Therefore, when choosing a table lamp, try not to choose products with a color temperature exceeding 4000K.

Color rendering is an important indicator of lighting quality. In indoor lighting, many standards require the color rendering index to be above 80. The color rendering index of sunlight is 100. The incandescent lamp has a color rendering index closest to sunlight, followed by OLED light sources (>90), and the color rendering index of LED is generally around 70-80. In order to improve the clarity of work and the fidelity of colors, and relieve eye pressure, you should preferably choose lamps with a color rendering index (Ra) not lower than 80. If you need to do things with high color requirements under the table lamp, such as drawing and color matching, it is recommended to choose a table lamp with a color rendering index of at least 90.

Regarding the issues of light source glare and uniformity, it is recommended that you choose diffuse planar light sources (OLED) instead of point light sources with strong beams. If the light is relatively uniform, there will be no glare, which can well relieve visual fatigue.

(Content reference: China Consumer News · China Consumption Network)

Appendix: The main reference standards for this comparative test include GB/T 9473-2008 "Performance Requirements for Reading and Writing Table Lamps", GB 50034-2013 "Standard for Lighting Design of Buildings", GB/T 31831-2015 "Technical Requirements for LED Indoor Lighting Applications", as well as relevant clauses of CQC 1601-2013 "Technical Specification for Visual Operation Table Lamps" issued by China Quality Certification Center, and the test was carried out in accordance with GB/T 16759-2008 "General Principles for Comparative Tests of Consumer Goods and Related Services".