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Why can an LED light set achieve the function of two types of lamps?

  • Author:Innotech
  • Source:Innolite
  • Release on :2018-07-17

Question 1:

A Toyota accident car was seriously damaged by the rear part of the rear-end collision, and the left combination taillight was damaged. The service technician did not find the brake light when changing the lamp, only found the left tail width lamp. So please come to the electrician to help find the brake light, the electrician pointed out that the left tail of the car is the left brake light. Originally a LE D lamp set, which has two functions of taillight (width indicator) and brake light. Why is an LED light group capable of realizing the functions of two types of lamps?


An LED light-emitting diode is a solid-state semiconductor device that converts electrical energy into visible light. The core of the LED is a packaged semiconductor wafer. The wafer consists of a P-N junction composed of two parts, a P-type and an N-type semiconductor. When a certain current passes through the wafer, the electrons are pushed toward the P region and recombined with the positively charged holes. At this time, the light energy is excited in the form of photons, which is the basic principle of LED lamp illumination.

Based on the above-mentioned principle of illumination, the LED light source has a special performance, that is, as long as the operating current of the LED is adjusted, the brightness of the lamp can be adjusted as needed, so that one LED group can realize conversion between multiple brightnesses, and realize multiple lamp groups. The function. Figure 1 shows the LED tail light on a car, which is composed of 15 LED light particles. This LED light group can be used as both a brake light and a width light for the tail of the vehicle. By changing the current intensity of the LED light-emitting diode through the changeover switch, the LED light particles can emit different brightnesses, thereby becoming different light sources.

The internal circuit of the LED light group shows that 15 LED light particles are used in order to obtain a large-area light-emitting effect, making it more suitable for the prompting function of a high-speed traveling vehicle. The 15 LED lamps are divided into 5 groups in parallel, and each group of 3 LED lamps is connected in series with a 120Ω resistor. The entire luminaire can be easily switched to a brake or taillight with a light switch. When the LED lamp is used as the rear wide lamp, the current passes through the 470Ω resistor, the current is only about 100mA, and the power is less than 2W. When used as the brake lamp, the circuit does not pass the 470Ω resistor, the measured working current is 280mA, and the whole lamp group consumes power. Less than 4W. The brightness of the brake light is enough to inform the rear vehicle 50m away: the car is implementing braking, please pay attention to deceleration in time. Switching between the two lights is extremely simple and convenient.

LED light source is a low-voltage microelectronic device, especially suitable for automotive 12V low-voltage DC power supply. If traditional incandescent lamps are used, each brake lamp consumes 21W, compared with the LED light source, which can save more than 80% of energy while achieving better brightness than incandescent lamps. At present, LED lights are used in more and more cars. It is hoped that the majority of riders and maintenance technicians will be familiar with and choose LED light (Plastic with Aluminum LED bulb supplier) sources.