In the LED packaging industry, the most troublesome problem for engineers should be the technical problem of white light color temperature. Why is this so? This has to start with the source of white light color temperature.
1. First of all, the production of white light.
Those who do LED packaging should know that white light is achieved after adding powder to the blue light chip (as for why the blue light chip needs to add powder, you can go to the relevant LED technology website to check). This is for a single chip. With the development of multi-chip integrated LEDs, if you want to make white light LEDs, there is another way, which is mixing light. The problem of mixing light technology is also an issue that many LED packaging manufacturers are actively concerned about.
2. The wavelength and color temperature of white light.
In most cases, we will not talk about the wavelength of white light. Because, white light, from the principle of light emission, is a mixed color light of seven colors. Therefore, we generally pay more attention to the color temperature of white light.
Color temperature is a scale that represents the color of the light source, and the unit is K (Kelvin). Color temperature has important applications in photography, videography, publishing and other fields. The color temperature of a light source is determined by comparing its color with a theoretical thermal blackbody radiator. The Kelvin temperature when the thermal blackbody radiator matches the color of the light source is the color temperature of the light source, which is directly related to Planck’s blackbody radiation law.
As far as LED packaging technology is concerned, the color temperature of the normal market is in two ranges: 6000-7000K (pure white) and 2000-3000K (warm white). Beyond this range, the light color will be blue. The higher the color temperature, the bluer and colder the light color; below this range, the light color will be warmer. Knowing this range, it is easy to explain the following question: What if I only need to make a 3500K white light LED chip? Then when packaging, can it be controlled within the range of 50K?
Why do we need to control this range? There is a reason. بشكل عام, if the color temperature is too different, the effect after the light source is lit will also be different. Generally, as long as the difference is 200K, it will be very obvious.
Test method: Put a piece of white paper in front of the light source (if your product is an RGBW four-in-one eight-pin LED chip), you will find that if the brightness changes significantly, it proves that the color temperature differs by at least 200K.
Different LED finished lamps and different lighting fields have different requirements for this color temperature. The requirements for LED stage lights will not be very obvious, because the main requirement is color, not color temperature; however, if it is an aquarium lamp, it will not work. Although aquarium lamps also have high requirements for color, relatively speaking, when appreciating the lighting effects of aquarium lamps, we are generally in a relatively quiet environment, and at this time our observation will be easier to capture the difference in light and dark of the light source.
3. The future of white light, technological breakthroughs are the key.
الآن, everyone should know that color temperature control is a difficult problem. For this color temperature problem, the best solution is not only for engineers to carefully control (adjust powder), but also requires higher technical support. An important source is the chip! When one day, the chip itself can reduce the demand for phosphors, then this technology and color temperature control will be easier.