What is the principle behind the low beams not turning off when the high beams are on?
2 Answers
When the high beams are turned on, the car's low beams also remain lit, primarily controlled by the headlight controller, which can be cumbersome if frequently switched back and forth. Compared to low beams, high beams have a longer range and greater light intensity, but their use should be determined based on the road conditions the car is traveling on. Usage of high beams: 1. On roads without central barriers or center lines, high beams should not be used when meeting an oncoming vehicle within 150 meters. 2. High beams should not be used when meeting non-motorized vehicles on narrow bridges or roads without central barriers or center lines. 3. High beams should not be used when turning at intersections controlled by traffic signals. 4. In low-visibility conditions at night, such as when there is no street lighting, poor lighting, or encountering fog, rain, snow, or dust, high beams should not be used when a following vehicle is traveling close to the vehicle in front in the same direction. 5. When overtaking at night, high and low beams should be used alternately to alert the vehicle ahead. 6. High beams are not recommended in well-lit urban areas.
I found that the car's high beam and low beam work together because the design uses a dual-filament bulb or a composite lamp assembly to ensure seamless lighting. Specifically, there are two filaments inside the bulb: one is the low-beam filament, which disperses light to cover the road at close range, and the other is the high-beam filament, which focuses light to illuminate the distance. When you switch to the high beam, the switch or electronic controller will power both filaments, so the low beam remains on. This avoids sudden darkness that could create a blind spot and improves driving safety. Especially at high speeds, having both beams working simultaneously allows you to see obstacles ahead and the surrounding environment clearly. If the design were improper, with the high beam operating independently, it could darken the nearby field of vision and cause accidents. Engineers arranged it this way for safety reasons, and the lighting system includes relay control to ensure smooth switching. Experienced drivers know that nighttime driving relies on this mechanism to reduce risks.
