Application Analysis of LED in Lighting Engineering
( 1. Department of Light Source and Lighting Engineering, Fudan University, Shanghai 200433; 2. China Lighting Society)
Abstract: Based on the principle and characteristics of LED illumination , this paper starts from the elements of shaping a reasonable aura, objectively analyzes how to properly apply LED according to the characteristics of LED in various lighting projects, and further promote the application of LED in lighting engineering. Key issues.
Keywords: LED, lighting engineering, health, comfort, dynamics, ergonomics
1 Introduction
LED was born in the 1960s. As a solid-state light source with great development potential, LED's long life, firm structure, low power consumption and flexible form factor have attracted more and more attention. From the initial stage of instruction application to LEDs, especially monochrome LEDs have been widely used in large-screen displays, signal lights and landscape lighting in recent years. So far, indications, signals and displays are still the most important areas of application for LEDs, and the amount of LEDs used in these areas is enormous. With the continuous development of LED technology, the light efficiency, color rendering, color temperature, power of single LED and luminous flux of LED module of white LED have made new breakthroughs. People are full of expectation for LED application in traditional field lighting. .
However, the application of LEDs in lighting engineering also faces a series of challenges. For example, the luminous flux of a single LED is difficult to meet the needs of general lighting, the unit cost is too high, the luminous efficiency is lower than that of a gas discharge lamp, the color difference is large, and the stability is insufficient. Etc. Although the results of laboratory research are frequently refreshed by various manufacturers, it still takes a certain amount of time for the market-oriented products that meet the lighting requirements. This is a fact that LED R&D personnel, manufacturers and users cannot avoid.
Therefore, in order to apply LEDs in lighting engineering, we must fully consider the principle and characteristics of LED lighting, proceed from the elements of shaping a reasonable aura, rationally utilize the advantages of LEDs, and flexibly apply LEDs so that different lighting projects can be fully utilized. The advantages of LEDs create excellent lighting engineering works.
Figure 1 LED lighting schematic
2 LED lighting principle and characteristics
The structure of the LED (Light Emitting Diode) is mainly composed of a PN junction chip, an electrode and an optical system, and is an electroluminescence light source. FIG. 1 is a schematic diagram of the illumination of the LED. When a sufficiently high forward DC voltage V is applied, the electrons and holes will overcome the barrier at the PN junction and flow to the P and N regions, respectively. At the PN junction, electrons and holes meet and recombine to produce luminescence, and the wavelength λ of the photon is determined by the band gap E.
λ=1240/E
The unit of E is electron volt (eV), and the unit of λ is nanometer (nm).