About twenty years ago, in the autumn of 1996, the first white light-emitting diodes (LEDs) were offered for sale.
|Shuji Nakamura FREng|
|Known for||Blue and white LEDs|
|Awards||Millennium Technology Prize (2006) Harvey Prize (2009) Nobel Prize in Physics (2014) Global Energy Prize (2015) National Inventors Hall of Fame (2015) Mountbatten Medal (2017) Zayed Future Energy Prize (2018)|
White light can be achieved with LEDs in three ways: Phosphor conversion, in which a phosphor is used on or near the LED to convert the colored light to white light. Color-mixed systems, in which light from multiple monochromatic LEDs (e.g., red, green, and blue) is mixed, resulting in white light.
Common LED colors include amber, red, green, and blue. To produce white light, different color LEDs are combined or covered with a phosphor material that converts the color of the light to a familiar “white” light used in homes. Phosphor is a yellowish material that covers some LEDs.
Almost all "white" LED grow lights on the market today are actually just a blue LED with a phosphor coating which converts much of the blue light into different colors.
History of the LED Bulb
The next year, in 1962, Nick Holonyak, Jr. (the “Father of the Light-Emitting Diode”) invented the first LED that produced visible, red light while working at General Electric.
(the “Father of the Light-Emitting Diode”) invented the first LED that produced visible, red light while working at General Electric. Throughout the 1960s, researchers and engineers continued experimenting with semiconductors with the goal of producing more efficient LEDs.
Pure White is a plain white without any warmth. Cool white produces a light similar to daylight, with a slightly blue tint. Some people like the cool white, while others like the more traditional warm white; it's a personal choice.
Commercially available LED units include wavelengths in the red, yellow, blue, and near infrared portions of the spectrum.
RGB LEDs can produce white light by mixing the primary red, green and blue lights together in theory. But the mixture includes blending and diffusion of colors, creating factitious white light. This kind of white light seems to be covered with fog. The hazy light will cause discomfort visual experience to people.
The enemy of the LED's phosphor is the heat and UV radiation it emits during operation. Over time, these two forces degrade the phosphor and break down its components. The result is a fixture that used to give off nice white light but is now a little off—perhaps a bit blue or pink or green.
The issue, the company said, is the result of a defective phosphor coating in the street light fixtures, which was designed to make the bluish color of the LEDs appear white. Over time, the coating wore off, causing the lights to shine purple instead.
Pure White (also known as 'commercial white' or 'bright white') – This is used in commercial applications and also for highlighting. Generally brighter than Daylight White, Pure White is in the range 5000K – 6500K (lower values are warmer) on the Kelvin scale.
When it comes to buying LED lamps, the colour ranges you get start at warm white, which is a more yellow colour, through to cool white, a more 'pure white' colour, through to daylight, which is more light a white with a blue hue.
It targets inflammation, accelerates tissue healing, and reduces scarring. White light is ideal for conditions such as acne, rosacea, psoriasis, eczema and hyperpigmentation. LED therapy uses light energy to stimulate your body's natural processes and promote healing from deep within.
Purple LEDs are manufactured using GaN substrates, and the chip is produced by placing GaN semiconductors on a GaN substrate. In short, this is a type of GaN-on-GaN LED. GaN semiconductors have better crystal quality, and higher purple LED luminous efficiency.
Essentially, all white LEDs are really blue LEDs that are coated with a substance (phosphors) that converts some of the blue light into longer, less energetic wavelengths. Because most lighting applications are for people, not plants, by far the greatest demand for LEDs is for white.
If all you're after are basic RGB colours with no requirement for a proper white then basic RGB LED strip is generally more cost effective, however if you do need white (for example for task lighting) then RGB+W is a better bet.
Exposure to all colors of light helps control your natural sleep-and-wake cycle, or circadian rhythm. More so than any other color, blue light messes with your body's ability to prepare for sleep because it blocks a hormone called melatonin that makes you sleepy.
It's well-documented that blue light can have a negative impact on your melatonin levels. Exposure to green and purple light could also potentially hinder your ability to fall asleep, but more research is needed to fully understand their effects.
Blue light may also kill acne-causing bacteria known as Cutibacterium acnes. Often blue and red light are used in combination to help fight acne — the blue light targeting the C. acnes and the red light targeting inflammation and redness.
Disadvantages of LED Bulbs
Most white LED bulbs emit a cooler, blue-tinted light — rather than the “warmer” glow that is associated with incandescent bulbs. Some people prefer “daylight” or “natural light” LED options. Some LED fixtures may create sharp shadows that may not be desirable in certain places in the home.
And since light being reflected by objects is what gives them a color, some think this means that the color pink doesn't really exist. In reality pink is an illusion created by our brains mixing red and purple light — so while we see the color pink, it doesn't have a wavelength.
“The advantage [of RGB] being that rather than just being set to one color from the factory, you get 16.8 million colors to choose from, so it's really up to your own imagination. Then, through software, you can then specify those colors per key, in zones or per game or application.
Research studies discovered red to be the best color light to help you sleep, because it increases production of melatonin as well as full darkness. On the other end of the spectrum, blue is the worst.