The Structure, Light Emitting Principle, and Advantages of LED Headlights

As an indispensable lighting device for night driving, car lights are increasingly regarded as the preferred product by more and more car manufacturers with the continuous development of LED technology. LED car lights refer to lamps that use LED technology as a lighting source inside and outside the vehicle. External lighting equipment involves multiple complex standards such as thermal limits, electromagnetic compatibility (EMC), and load shedding testing. These LED car lights not only improve the lighting effect of the vehicle, but also create a more comfortable interior environment.

Construction of LED headlights
The basic components of LED include gold wire, LED chip, reflective ring, cathode wire, plastic wire, and anode wire.
The key part of LED is the chip composed of p-type semiconductor and n-type semiconductor, and the structure formed between them is called pn junction. In the PN junction of certain semiconductor materials, when a small number of charge carriers recombine with the majority of charge carriers, excess energy is released in the form of light, converting electrical energy into light energy. When a reverse voltage is applied to the pn junction, it is difficult to inject a small amount of charge carriers, so luminescence will not occur. This type of diode manufactured based on the principle of injection based luminescence is called a light-emitting diode, commonly abbreviated as LED.

The luminous process of LED
Under the forward bias of LED, charge carriers are injected, recombined, and radiated into the semiconductor chip with minimal light energy. The chip is encapsulated in clean epoxy resin. When current passes through the chip, negatively charged electrons move to the positively charged hole region, where they meet and recombine. Both electrons and holes simultaneously dissipate and release photons.
The larger the bandgap, the higher the energy of the generated photons. The energy of photons is related to the color of light. In the visible spectrum, blue and purple light have the highest energy, while orange and red light have the lowest energy. Due to the different band gaps of different materials, they can emit light of different colors.
When the LED is in forward working state (i.e. applying forward voltage), current flows from the anode to the cathode of the LED, and the semiconductor crystal emits light of different colors from ultraviolet to infrared. The intensity of light depends on the magnitude of the current. LEDs can be compared to hamburgers, where the luminescent material is like a “meat patty” in a sandwich, and the upper and lower electrodes are like bread with meat in between. Through the study of luminescent materials, people have gradually developed various LED components with higher light color and efficiency. Although there are various changes in LED, its luminescent principle and structure remain basically unchanged. Jinjian Laboratory has established a testing line covering chips to lighting fixtures in the LED optoelectronic industry, providing one-stop solutions that cover all aspects from raw materials to product applications, including failure analysis, material characterization, parameter testing, etc., to help customers improve the quality, yield, and reliability of LED products.

Advantages of LED lights

1. Energy saving: LEDs convert electrical energy directly into light energy, consuming only half of traditional lamps, which helps reduce fuel consumption and avoids damage to car circuits due to excessive load current.
2. Environmental protection: LED spectrum does not contain ultraviolet and infrared rays, has low heat generation, no radiation, and low glare. LED waste is recyclable, mercury free, pollution-free, safe to touch, and is a typical green lighting source.
3. Long lifespan: There are no loose parts inside the LED lamp body, avoiding problems such as filament burning, thermal deposition, and light decay. Under appropriate current and voltage, the service life of LED can reach 80000 to 100000 hours, which is more than 10 times longer than traditional light sources. It has the characteristics of one-time replacement and lifelong use.
4. High brightness and high temperature resistance: LEDs directly convert electrical energy into light energy, generate less heat, and can be safely touched.
5. Small size: Designers can freely change the pattern of the lighting fixtures to increase the diversity of car styling. LED is highly favored by car manufacturers due to its own advantages.
6. High stability: LEDs have strong seismic performance, are encapsulated in resin, are not easily broken, and are easy to store and transport.
7. High luminous purity: LED colors are vivid and bright, without the need for lampshade filtering, and the light wave error is less than 10 nanometers.
8. Fast response time: LEDs do not require a hot start time and can emit light in just a few microseconds, while traditional glass bulbs require a delay of 0.3 seconds. In applications such as taillights, the fast response of LEDs helps effectively prevent rear end collisions and improve driving safety.