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Changes in the Role of Leds in Automotive Lighting Applications (1)

Jun. 11, 2020

 Super Bright Headlamp

Automotive LED headlights supplier will share this article for you.

1 Introduction

Most roads in North America and other parts of the world are not illuminated by road lighting systems that are fixed to the mast. Therefore, car lighting is a key component for safe driving at night.

The performance requirements for automotive headlights are based on standards and recommendations issued by the Association of Automotive Engineers (SAE) and similar industry organizations. These requirements stipulate the minimum or maximum luminous intensity of illumination from the center of the vehicle lighting system in different directions.

Similar photometric performance requirements exist in countries outside North America; these regulations may differ in details, but all specify the luminous intensity, the purpose is to ensure that the vehicle lighting system provides the driver with enough light to see the road, and minimize the The glare of other drivers, and ensure that vehicle signal lights can be detected in a timely and clear manner.

2. Headlights

For the super bright headlamp that provides illumination to the front of the vehicle, two are required and need to be installed as far as possible. Each headlamp must meet the same performance requirements. There are two main types of beam patterns: high beam and low beam. The requirements for high beams are higher intensity and smaller maximum intensity values. In addition, the high beam has a symmetrical beam pattern. In contrast, the low beam has an asymmetric beam pattern, and the stricter maximum value tends to the left (this is true in North America; if the country is on the left, the beam pattern is reversed from left to right).

Most North American headlights require the cut-off boundary on the right to be at the same height as the headlights. The left cut-off boundary is usually lower than the right boundary to reduce the amount of light entering the eyes of the oncoming driver. The "dazzling" cut-off boundary of the low-beam headlight pattern limits the driver's visibility in front.

When the driving speed exceeds 60-65 km/h, it may be difficult for the driver to use low-beam headlights to detect some potential dangers in time and stop. In this case, the high speed of light is guaranteed unless the approaching vehicle is within 100 meters. However, most drivers do not make full use of high beam headlamps.

Since the cut-off boundary of the low-beam headlamp pattern is clear, the vertical target is an important factor to achieve optimal performance. For example, in the United States, most states do not require headlights as part of security inspections. A recent study of vehicle vertical targets found that most vehicles have at least one headlight with poor targets. When the target is too high, the headlights may cause uncomfortable glare. When the target is too low, the driver's visibility in front is affected.

The adaptive lighting system is based on the speed of the vehicle and the angle of the driving direction to automatically adjust the steering angle of the low beam light to expand the effective lighting range when the vehicle turns. The automatic level adjustment function ensures that the light always shines on the ground ahead regardless of the load. Some vehicles have turn and curve lights; bend lights sometimes use mechanical elements to direct one or two headlights toward the road curve.

Some European vehicles are equipped with a "township" headlamp beam mode, which has a lower maximum luminous intensity and a wider distribution than most low beams, which can help drivers detect pedestrians when driving at low speeds in the city. The requirements for adaptive lighting systems in most countries are based on the United Nations Economic Commission for Europe (ECE) Vehicle Regulation No. 123. The United States' "Federal Motor Vehicle Safety Standard 108" currently has reservations about adaptive lighting systems.

At present, most automobile headlights use a reflector or a filament source of a projector optical system (tungsten halogen or simpler halogen) to generate the necessary beam pattern. The second is China automobile LED headlights. Regardless of the light source used, all headlights need to meet the same photometric requirements.

3. Signal lights

The vehicle needs to have signal lights so that the driver can alert others when braking and turning during the day and night. Now, more and more vehicles use LED for signal lighting. Different signal lights have different requirements for color and luminous intensity. The US Federal requirements for vehicle signals are based on SAE standards and recommendations.

The performance requirements of European automotive signal lights are not much different from North America in terms of color and luminous intensity, but there is one exception. In the United States, the signal lights on the back of the vehicle may be red or yellow, with different intensity requirements, depending on their color. In most other parts of the world, the relay signal must be yellow.

Yellow rear turn signals tend to have fewer collisions, probably because their luminous intensity is higher than red rear turn signals, or because yellow makes them easier to distinguish between brake lights and tail lights. The National Highway Traffic Safety Administration (NHTSA) is considering whether it is necessary to turn the yellow turn signal on all rear-mounted cars.

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