Recently, everyone is very concerned about caring for the eyes. A few days ago, Weibo also appeared in the world's first hot search for teenage myopia. The number of myopia patients in China is as high as 600 million, and the myopia rate of primary school students is also close to 40%. The child’s eyesight sounded the alarm.
It seems that there have been doubts about the lighting of WiT lamps recently. Take this opportunity to share the knowledge of light and love.
We all know that there are two light-related factors in the care of the eye that are of concern: no blue light hazard, sufficient light (brightness and range).
Let's talk about Blu-ray first. This is also a question that everyone is most concerned about.
What is the blue light? Is it the blue light in the rainbow red orange yellow green blue blue purple? Where does the blue light exist?
Yes, the sun is a composite light of seven colored lights. Blu-ray is one of them. Without any kind of color light, it can't be combined into sunlight. Accurately, blue light refers to HEV light (High-energy visible light). ), is one of the sun's composite rays, that is, high-intensity, high-frequency (wavelength 400-500nm) blue-violet visible light.
So it is a kind of light that nature has. It just hides in the sun and feels invisible. We are exposed to the sun almost every day, and we are exposed to blue light every day.
Every day, when you are exposed to the sun, isn't it necessary to receive blue light every day? No, no, any behavior that is open to doses is a hooligan.
What is the blue light hazard? How to carry out Blu-ray hazard certification? Let us look at the picture together.
The black curve represents the blue light hazard function curve, and the other colors represent the spectral curves of different light sources. As can be seen from the figure, various light sources contain blue light. The intensity of blue light harming the human eye depends on the spectral curve of various light sources. The area of the gray area is calculated.
That is to say, blue light does have harm, but whether it can cause harm to the human eye, in addition to watching the intensity of blue light, it is also necessary to pay attention to the duration of illumination. Even low-intensity blue light, too long exposure time will cause damage to the eyes.
So how do we define the level of blue light hazard? The following is the blue hazard level defined in IEC 62471.
RG0 is the highest level of safety. It uses extreme environmental testing. The eye is 20cm away from the light source. It adheres to the direct-view light source (lighting bead) for 2.7 hours without damage. It is considered to be RG0.
Let us review the definition of blue light (HEV light). Blue light is present in all light sources, and it will cause harm to the human eye, which is related to the intensity of illumination and the illumination time.
Read with me: Blu-ray hazard depends on the dose and duration. For a long time, excessive blue light is harmful to the eyes. (Key points, to be tested.)
So how does our country detect the blue light hazard of lamps? This is about to talk about 3C certification.
3C certification is China's compulsory product certification. It is a safety certification. It has been added to the Blu-ray hazard detection project since 2017. It is worth mentioning that at present, only China and the European Union will compulsory detection of blue light hazards in lamps, Japan, the United States, etc. No. This also shows that our country's requirements for product quality and control standards continue to improve. (Proud face)
So what is the specific certification for Blu-ray hazard in 3C certification? What is the basis?
IEC/TR 62778: 2014 (Blue Light Hazard Assessment for Light Sources and Luminaires) referenced by 3C certification. There is also an international standard IEC 62471:2006 (Photobiosafety for luminaires and luminaire systems) is also a standard for detecting blue light hazards.
What is the difference between these two standards?
The first one is only for blue light hazard detection, the second one can detect all colors of light, ie full spectrum detection.
Which institutions can detect blue light hazards? Here are a few domestic and international authoritative testing institutions.
To select these lights, you must look for these certifications. Through the above three certified products, the safety is guaranteed and more trustworthy.
After finishing the blue light, let's talk about the light intensity and range.
First think about two issues.
Why use table lamps? Because dark, eyes are inevitably close to reading in the dark, long time close reading, children in the sensitive period of visual development, it is easier to have nearsightedness. So we say that the brightness is enough. Primary school classroom lighting and lighting standards GB_7793-2010 requires desktop brightness of more than 300lux)
Where is the table lamp lighting used?
The ergonomic diagram above shows that the maximum range used by the human body during work and study is a rectangular area. (There is a prize-free quiz title here: Why is the study table, the work table mostly rectangular instead of round and square?)
But think about the table lamp we use. The lamp head is mostly round. The area that is illuminated is also round. It is only concentrated in a small area in the middle of the table. This is not suitable for ergonomics and practical use.
Therefore, now the lighting industry is increasingly advocating and promoting long strip lighting design. For example, BenQ WiT table lamp and Yamada lighting use this design to make the illumination range elliptical, covering the entire desktop, avoiding the desktop side bright and dark, the eyes are in the light and dark. Eye fatigue caused by switching back and forth.
The US IESNA (North American Lighting Association) requirements for the area of the home page reading and writing lighting are as follows: The main working surface area is 360mm*310mm, and the secondary working surface area is 610mm*910mm.
Therefore, it is recommended that when selecting the desk lamp, the priority illumination range is elliptical, which can cover the desk lamp of the study work area.
Having said that, there are two things to focus on: Blu-ray hazard and lighting brightness.
Review it:
1. Blu-ray hazard depends on the dose and duration. For a long time, excessive blue light is harmful to the eyes. No Blu-ray hazard certification, please look for international authoritative testing institutions: CCIC, Intertek, Swiss General Notary ( SGS) and so on.
2. Desktop illumination can not only look at the brightness data of the circular area. The table lamp with ergonomic elliptical illumination design should be preferred, pay attention to the brightness coverage of the whole learning work area.
In the era of information explosion, it is more and more difficult to obtain accurate information. However, we can identify new and international scientific knowledge by identifying the accreditation of international and domestic authorities, and identify and screen. The bright future can be expected!
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