The LED power supply is small and lightweight, low driving voltage, full color, long life, high efficiency, vibration resistance, easy to control light and other characteristics, which provide superior conditions for lighting systems designed for different places and purposes. People are accustomed to looking at things under the sun. For general lighting, what people need is mainly a light source close to the quality of sunlight, so white LED is an important indicator of semiconductor lighting technology.

Because a single LED has low power and low brightness, it is not suitable to be used alone. For this reason, multiple LEDs must be assembled together to design a practical LED lighting system. However, there is still a certain distance between white LEDs and general lighting requirements, and there are still many technical and cost issues that need to be resolved urgently.

The main technical overview of semiconductor lighting system

The heat management of the luminaire system is generally referred to as a cold light source. This is because the principle of LED light emission is that electrons directly emit photons through recombination without the need for heat. However, due to the existence of Joule heat, LEDs emit heat at the same time, and for high-power and multiple LED applications, the heat accumulation is too small and cannot be underestimated. LEDs are different from traditional lighting sources such as incandescent lamps and fluorescent lamps. Too high temperature will shorten or even end its service life. Moreover, LEDs are temperature-sensitive devices, and their efficiency drops sharply when the temperature rises. Therefore, system structure design and heat dissipation technology development are also issues that LED applications need to face. Since forced air cooling is generally undesirable in light sources, as the input power increases, heat sinks and other methods to enhance natural convection cooling play an increasingly important role in the design of LED lamps and light sources.

Improve color rendering

At present, white light LEDs generally use blue light emitting LEDs to superimpose yellow light emitting yttrium aluminum garnet (YAG) phosphors excited by blue light to synthesize white light. Since its luminescence spectrum only contains blue and yellow spectra, there are problems of high color temperature and low color rendering index, which does not meet the requirements of general lighting. The sensitivity of the human eye to chromatic aberration is much higher than the sensitivity to light intensity. For lighting, the color rendering of the light source is often more important than the luminous efficiency. Therefore, adding an appropriate amount of red-emitting phosphors and maintaining a high luminous efficiency is an important issue in LED white light illumination.

The secondary optical design of the lamp system

Traditional lamps have long used incandescent lamps and fluorescent light sources as references to determine the optical and shape standards of the lamps. Therefore, the LED lamp system should consider abandoning the traditional lamps and the assembly method of the LED light-emitting module, and fully consider its optical characteristics. It is specialized for LED light sources. Design different lamps.

The design content of the optical system mainly includes the following aspects:

Determine the shape of the optical system, the number of LEDs and the size of the power according to the needs of the lighting object and luminous flux;

Combine several LED light-emitting tubes to design a "secondary light source" of point light source, ring light source or surface light source, and calculate the illumination optical system according to the combined secondary light source;

It is very important to control the light distribution of each LED tube on the "secondary light source" that constitutes the design of the illumination optical system.

Since the light beam emitted by the LED is concentrated, it is easier to control and does not require a reflector to focus light, which is beneficial to reduce the depth of the lamp. For example, the use of a flat mirror optical system can illuminate a large surface with only 1 or 2 LEDs, and the depth of the lamp is very thin; and the use of light guide technology, the LED is directly installed next to the light pipe, which can greatly reduce the light source and other components The occupied volume is made into an ultra-thin lamp.