Does the blue light of LED lights really damage the eyes?

     LED lamp is a new type of light source after incandescent lamp, fluorescent lamp and energy-saving lamp. It has high luminous efficiency. However, many people do not understand its luminous principle and spectral characteristics, and it is inevitable that they will worry about whether the light it emits will be damaged. eye.

     Three colors of LED

     In terms of spectrum, the light emitted by LEDs is very different from the light emitted by traditional incandescent lamps and fluorescent lamps. The so-called "spectrum" means that the light emitted by an object corresponds to a "rainbow".

      The light emitted by traditional incandescent lamps and fluorescent lamps has the same 7 colors as the sun's rays: red, orange, yellow, green, blue, blue and purple.

    However, the general LED light only has three colors of "RGB", where R is red, which means red light; G means green, which means green light; and B means blue, which means blue light.

     These three colors of LEDs are important and basic to the "blue LED" between 400nm and 500nm.

     Where is the Blu-ray?

     Look at the "rainbow" picture above. From left to right, there are ultraviolet, visible and infrared in order. The wavelength range of visible light is between 400 nanometers and 700 nanometers, and the wavelength range from 400 nanometers to 500 nanometers is blue, so this band is called blue light.

     The basic unit of light is called photon. The wavelength of photon is inversely proportional to frequency. Blue light has a short wavelength, so the frequency is high.

     Blue LED technology has won the Nobel Prize in Physics

    The blue LED technology was only developed in 1998, and this technology won the 2014 Nobel Prize in Physics. It seems that the tall blue LED is made by encapsulating GaN chips and yttrium aluminum garnet (YAG) together. The GaN chip emits blue light, the wavelength λ is equal to 465 nm, and the wavelength bandwidth is about 30 nm.

    How does a white LED emit white light?

     So, how does the white LED in the home produce white light? As mentioned above, the energy of blue photons is high, so it can be used to excite fluorescence. Generally, the blue light produced by the blue LED is hit on the phosphor to produce yellow light.

    After the yellow light is excited by the blue light, they are emitted from the LED together, and we will feel as if we see white light. In fact, this is just a composite light of blue and yellow mixed together.

     Because of this principle, many manufacturers directly increase the intensity of blue light in order to increase the brightness of white light LEDs, so that the yellow light will increase accordingly, and then the brightness of the formed white light will increase, but this will cause us to Explain the "excessive blue light" problem.

      Actual measurement of LED light spectrum

      The following figure is the measured spectrum of different types of white LEDs. We can see that the "blue light" between 400nm and 500nm has a strong peak.

     This shows that the LED looks white, but in fact its spectrum does contain a strong blue light component.

     The effect of blue light on the retina

     So, since blue light is the "mother" of white LEDs, how do the eyes feel about blue light?

      The tissue in the human eye that receives light is called the retina. If the brightness of the 400-500 nm blue light band in the light source is too high, the eye may cause photochemical damage to the retina after looking directly at the light source for a long time.

     This kind of damage is mainly divided into two categories: damage caused by the direct reaction of blue light with the visual pigment in the visual photoreceptor cells, and damage caused by the reaction of blue light with the lipofuscin in the retinal pigment epithelial cells. These photochemical reactions will produce a large number of cytotoxic free radicals, which damage the normal growth and work of retinal cells.

    The detection standard of LED blue light excessive in life

    Generally speaking, products marketed by regular manufacturers through national quality inspections will not have the hidden danger of excessive blue light. However, some LED lamp manufacturers do not pay attention to controlling the intensity of blue light. The blue light in the LED lamps they produce is "excessive", which causes blue light radiation damage to the eyes.

    In life, there are many light sources that can emit blue light-Yuba, flat panel displays, LED neon lights, fluorescent lights, liquid crystal displays, ipads, large-screen mobile phones, etc. all have background light sources, and they all contain short-wave blue light. If the blue light is "excessive", it will affect the retina, so you should avoid looking directly at the light source with your eyes, and pay attention to the time of use, close your eyes and rest every 20-30 minutes.

      For the LED lamps sold on the market, how to judge the excessive blue light of the LED is a complicated problem.

    From the perspective of eye protection, it is recommended that you choose lamps with low blue intensity when buying LED lights. Those who have the conditions can use a spectrometer to measure the spectrum of the light emitted by the LED lamp-if the intensity of the blue light emitted by this LED lamp is much stronger than the blue light in the sun, don't buy it.

      It is a new type of light source after incandescent lamps, fluorescent lamps and energy-saving lamps. It has high luminous efficiency, but many people do not understand its luminous principle and spectral characteristics, and it is inevitable that the light emitted by it will damage the eyes.

    Three colors of LED

     In terms of spectrum, the light emitted by LEDs is very different from the light emitted by traditional incandescent lamps and fluorescent lamps. The so-called "spectrum" means that the light emitted by an object corresponds to a "rainbow".

    The light emitted by traditional incandescent lamps and fluorescent lamps has the same 7 colors as the sun's rays: red, orange, yellow, green, blue, blue and purple.

     However, the general LED light only has three colors of "RGB", where R is red, which means red light; G means green, which means green light; and B means blue, which means blue light.

     Among the three colors of LEDs, the "blue LED" between 400nm and 500nm is the most important and basic.

    Where is the Blu-ray?

      Look at the "rainbow" picture above. From left to right, there are ultraviolet, visible and infrared in order. The wavelength range of visible light is between 400 nanometers and 700 nanometers, and the wavelength range from 400 nanometers to 500 nanometers is blue, so this band is called blue light.

    The basic unit of light is called photon. The wavelength of photon is inversely proportional to frequency. Blue light has a short wavelength, so the frequency is high.

     Blue LED technology has won the Nobel Prize in Physics

    The blue LED technology was only developed in 1998, and this technology won the 2014 Nobel Prize in Physics. It seems that the tall blue LED is made by encapsulating GaN chips and yttrium aluminum garnet (YAG) together. The GaN chip emits blue light, the wavelength λ is equal to 465 nm, and the wavelength bandwidth is about 30 nm.

     How does a white LED emit white light?

    So, how does the white LED in the home produce white light? As mentioned above, the energy of blue photons is high, so it can be used to excite fluorescence. Generally, the blue light produced by the blue LED is hit on the phosphor to produce yellow light.

     After the yellow light is excited by the blue light, they are emitted from the LED together, and we will feel as if we see white light. In fact, this is just a composite light of blue and yellow mixed together.

    Because of this principle, many manufacturers directly increase the intensity of blue light in order to increase the brightness of white light LEDs, so that the yellow light will increase accordingly, and the brightness of the final white light will also increase, but this will cause us to Explain the "excessive blue light" problem.

    Actual measurement of LED light spectrum

    The following figure is the measured spectrum of different types of white LEDs. We can see that the "blue light" between 400nm and 500nm has a strong peak.

     This shows that the LED looks white, but in fact its spectrum does contain a strong blue light component.

    The effect of blue light on the retina

   So, since blue light is the "mother" of white LEDs, how do the eyes feel about blue light?

    The tissue in the human eye that receives light is called the retina. If the brightness of the 400-500 nm blue light band in the light source is too high, the eye may cause photochemical damage to the retina after looking directly at the light source for a long time.

    This kind of damage is mainly divided into two categories: damage caused by the direct reaction of blue light with the visual pigment in the visual photoreceptor cells, and damage caused by the reaction of blue light with the lipofuscin in the retinal pigment epithelial cells. These photochemical reactions will produce a large number of cytotoxic free radicals, which damage the normal growth and work of retinal cells.

    The detection standard of LED blue light excessive in life

     Generally speaking, products marketed by regular manufacturers through national quality inspections will not have the hidden danger of excessive blue light. However, some LED lamp manufacturers do not pay attention to controlling the intensity of blue light. The blue light in the LED lamps they produce is "excessive", which causes blue light radiation damage to the eyes.

     In life, there are many light sources that can emit blue light-Yuba, flat panel displays, LED neon lights, fluorescent lights, liquid crystal displays, ipads, large-screen mobile phones, etc. all have background light sources, and they all contain short-wave blue light. If the blue light is "excessive", it will affect the retina, so you should avoid looking directly at the light source with your eyes, and pay attention to the time of use, close your eyes and rest every 20-30 minutes.

    For the LED lamps sold on the market, how to judge the excessive blue light of the LED is a complicated problem.

     From the perspective of eye protection, it is recommended that you choose lamps with low blue intensity when buying LED lights. Those who have the conditions can use a spectrometer to measure the spectrum of the light emitted by the LED lamp-if the intensity of the blue light emitted by this LED lamp is much stronger than the blue light in the sun, don't buy it.