LED light mixing scheme and deep analysis of simulation technology

Fresh lights have become more diverse in order to meet the lighting needs of fresh foods of all colors. Although the LED light source of the special spectrum is theoretically feasible, it is impossible to realize the LED products of each special spectrum; therefore, many fresh lights will still adopt a light mixing scheme. However, in order to obtain a suitable light mixing scheme, the usual calculation method is very cumbersome; in this paper, the existing white LEDs and color LEDs are reasonably selected, and the mixed color spectrum is obtained by using LightTools simulation, and the color parameters are analyzed and evaluated to obtain a suitable one. Fresh light mixing scheme and performance indicators.

With the further development of solid-state lighting, people's requirements for lighting quality are getting higher and higher. Many lighting fields have proposed personalized spectral requirements. The lighting of fresh lights in food is a good example. We know that under the lamp with low color and high color temperature, the face will look pale and lifeless. This is the same in food. With the inappropriate lighting, the fruits and food in the supermarket will become strange and unsatisfactory. Not only will it affect the business, but it will also be wasted because of the shelf life of the product; under the appropriate fresh light, the color of the food can be better restored, making it look fresher and more delicious, making customers more willing to buy Therefore, fresh lights are very important in the field of food lighting. LEDs are an ideal source of light in applications due to their easy access to a wide range of spectral colors.

The presence of a variety of monochromatic optical chips and the use of special phosphors in the blue chip can make most of the spectrum realistic. But for a single LED, not every spectrum of LEDs will become a product, because the market demand for each particular spectrum of LED is generally not very large; even if there is a product, the price will be higher, and it is possible There is a supply issue. Relatively speaking, the color mixing scheme is more feasible. Since only conventional LEDs are needed, the light source cost is lower, the scheme is flexible, and the supply is more reliable.

We usually use color coordinates, CCT, CRI, and CQS to evaluate color. In addition to the color rendering index of the conventional 8 standard color samples, CRI also has a color rendering index of 7 special color samples, and these 15 color samples are relatively unsaturated color samples, the first 8 parameters The average value is our usual color rendering property Ra. For example, R9 characterizing red light ("strongly") is not within the characterization of Ra, so even if the Ra is large, as long as its spectrum does not have enough red light. The value of R9 will also be low. NIST (National Institute of Standards and Technology) also found that even if a light has good color rendering properties for unsaturated colors, its color rendering properties for saturated colors may be poor; NIST found that only some saturated colors were selected. As a new set of color samples, it can guarantee the accurate characterization of color rendering, and propose a new method CQS (ColorQualityScale) for characterizing color rendering, which uses 15 kinds of saturated colors distributed throughout the visible spectrum. For its color. This article will use the two sets of methods to characterize color rendering to analyze the results after color mixing.

Given the spectrum, the various color information described above can be obtained, so the spectrum covers more comprehensive color information. For mixed-color lighting solutions, the spectral information is very important, but how to get it is more convenient?

“First of all, although it can be obtained by measurement, it needs to make a sample lamp, which includes custom PCB, preparation of heat sink and purchase of power drive, welding and assembly steps. Finally, the measurement is complicated and time consuming, and it is difficult to adjust the solution again. not flexible.

"Secondly, the calculation method is also very tedious. The spectral data is usually normalized, and the ordinate is related to mW (not lm); and the radiation characteristics of LEDs are different, such as white LEDs usually with luminous flux (lm), red Light is characterized by radiated power (mW), making the calculations more complicated.

“Finally, the simulation method in this article, with the help of LightTools tool simulation, not only can simply get the mixed color spectrum results, but also can get other color parameters to help us analyze and evaluate the solution.

Of course, the optimal spectrum required will vary with the subject being treated. Let's take the example of lighting a deep red apple. The fruit merchant hopes to get the right amount of deep red light doping, making the apple look rosy and delicious. At the same time, we must also emphasize that there are many kinds of red light. When selecting a red light source, we must first ensure that the correct dominant wavelength and spectral information are available, so that the mixed light scheme matches the lighting requirements.

In order to achieve our expected mixed-color spectrum results, we must first select the appropriate LED light source. OSRAM has a wide range of colorful products (including high-power OSLON series and medium-power DurisP5), especially in the case of red light, there are three bands of products; white LEDs also have three color rendering indexes and various color temperatures. Therefore, this article takes its product as an example, selects the red LED of the appropriate dominant wavelength and the white LED of the appropriate spectrum to obtain their spectral information, and simulate it by LightTools software.