陈小宁的博客

汽车的前灯

开车的人都知道，在汽车的所有灯光中，虽然后灯是带有刹车灯的部分，很重要。但是，汽车的前灯也非常重要，因为它要给驾驶员指明方向，并给旁边的车一些必要的指示，特别是在黑暗中，更是驾驶员安全驾车的一种保障。

汽车主要的前灯有三个：近光灯、远光灯和转向灯。前两个是为了在黑暗中照路，后者则是为告诉旁边的车我要转弯了。在使用Tesla的自动驾驶时，黑暗中它会自动调整远光灯和近光灯，在没有近距离前车或对面有车的情况下，远光灯会自动打开，为的是照得更远、更宽，自动驾驶处在更加高的有效范围内。而在绝大多数情况下由近光灯掌控汽车前进。

其实，汽车还有另一个前灯，绝大多数是必备的，名字是示宽灯。这个灯不太亮，但位于车前后的角落，很多车只要打开车钥匙，不用发动汽车它就亮了。Tesla的示宽灯在打开车门后会亮起，若车未启动，则会在一定时间后自动熄灭。

早先的车还有一个必备的灯，雾灯，目的是为了在迷雾的恶劣天气下能指示车的存在，给对面或附近的车做指示用，因为黄颜色的穿透力最强，这与交通灯里黄灯作为警告的作用相同。

特殊的车还会有特殊的灯存在，比如国产212吉普车和一些军用卡车，它的右前方会有一个小小的像雨棚一样的灯，名曰防空灯，里面左右还有两个箭头，为对面的车作为警示，但这是个盖子，也可以打开作为照明灯用。如今现代的防空灯更有效，使用半导体代替过去的灯丝。

半导体技术提高了电能利用效率，因此许多大型车和摩托车使用了大量装饰灯，远远看去就像一列彩车，气势磅礴，走近一看不过是一辆单车，就连车底下都亮着单色或变色的灯，照亮着完全没有必要看的地方和内容。而且，只有在夜间才有它能显示出来的个性，看众除了不得已外出的，就剩下同样愿意行夜路的了。

老式车灯光控制复杂，每种灯都有独立开关。例如公交车，司机面前常有十多个开关，分别控制灯光和车门。过去的拉伸式开关操作繁琐，容易失误。后来改为按键式，操作简化。如今，大多采用旋转或拨动式开关，杜绝误操作。而高端车型则进一步引入计算机智能控制，提高了驾驶安全性。

常在夜间行车的人都知道，最烦的就是同向后面的车和对面来的车开远光灯，炫目的灯光会使驾驶员看不清前面的路况，会驾驶车辆出事的概率。前方的车是直射，后面的车则是通过反光镜或后视镜的光进入驾驶员眼睛，对此的策略只有后视镜的偏光，靠特定角度改善光线。不过，也有很多车不再使用手动偏光镜片，比如Tesla，因为有其他方法解决，比如自动驾驶等。

可以说在不该开远光灯时开了远光灯的人，要么是不懂交通规则，要么是故意的。曾有一个朋友说，远光灯就是可以随时开的，可见他根本没把交规中车灯的使用规则记住，而且因为他驾驶的是美式卡车，座位很高很难体会行车时被强光照射的痛苦。还有一类人，黑天开车就打开远光灯，特别是一些老年人，总想自己能看得远一点。殊不知，违章开远光灯可能会给自己带来麻烦，比如，对方在你的强光照射下，车辆可能失控，不论是顺行还是逆行都有可能。

开远光灯的确可以延伸可视的距离，就如站得高看得远一般，但凡事总是利弊相互存在，既然车设计了两种灯光，就必然有其存在的理由。近光很容易让驾驶员看清附近的细节，远光则是为车辆能快速行驶指明方向，这一远一近都有安全因素在内，缺一不可，只有合理地使用它们才有安全的保障。Tesla在自动驾驶状态会根据情况自动切换它们的使用。

前一段我写过一篇关于远光灯的博文，是因为我看到了一类车的远光灯中加装了传感器，可以根据对面来车的情况自动关闭远光。同时还可根据车子转向将大灯自动偏向转弯方向，对于驾驶员来说是一种福利，能帮助夜间行车提高安全系数。

汽车无论改成什么样式，车灯都是必不可缺的部件。灯光是汽车的眼睛，它为驾驶员提供视野，也为道路传递安全信号。合理使用灯光，不仅是对自己的保护，也是对他人的尊重，还能体现出驾驶员的素质和人品。

Car Headlights

Every driver knows that among all the lights on a car, while the taillights with brake lights are crucial, the headlights are equally important. They guide the driver and signal other vehicles, especially in the dark, ensuring safety during driving.

There are three main types of car headlights: low beam, high beam, and turn signals. The first two are used to illuminate the road in darkness, while the turn signals inform other vehicles of intended turns. For cars like Tesla, during nighttime driving with autopilot engaged, the system automatically adjusts between high beams and low beams. High beams are activated in the absence of nearby vehicles or oncoming traffic to provide a wider, farther range of visibility, enhancing the effectiveness of autonomous driving. In most cases, however, low beams are sufficient for regular driving.

In addition to these, most cars are equipped with a less prominent light called the position light (or parking light). This light isn’t very bright but is located at the corners of the car, both front and rear. It often lights up automatically when the car key is turned, even without starting the engine. On Tesla vehicles, the position lights turn on when the door is opened and turn off automatically after a while if the car isn’t started.

Older cars also came with fog lights as standard, designed for visibility in foggy or adverse weather conditions. Yellow light, with its superior penetration, was used due to its efficiency, similar to the warning role of yellow lights in traffic signals.

Special vehicles sometimes have unique lights. For example, older Chinese-made military jeeps (like the 212) and trucks had a small, covered light on the right front side called an “anti-aircraft light.” This light featured directional arrows inside and could be used as a warning signal for oncoming vehicles. It could also double as a utility light when the cover was removed. Modern anti-aircraft lights have evolved, replacing filaments with more efficient semiconductors.

Semiconductor technology has greatly improved energy efficiency. Today, many large vehicles and motorcycles are adorned with decorative lights, making them appear as grand as parade floats from afar. However, upon closer inspection, they’re often just ordinary vehicles, albeit with lights illuminating areas that don’t necessarily require visibility. These lights only showcase their aesthetic appeal at night, catering to either late-night travelers or fellow night drivers.

Older vehicles often had more complex light controls, with each type of light requiring a separate switch. For example, older buses featured over a dozen switches for various lights and doors. Pull switches used in the past were cumbersome and prone to error. Over time, these were replaced by button switches, simplifying operations. Today, most vehicles use rotary or toggle switches to prevent misuse. High-end cars have further adopted computer-controlled systems, enhancing safety.

Experienced nighttime drivers know the frustration of vehicles misusing high beams, whether from behind or from oncoming traffic. The dazzling lights can obscure the road ahead, increasing the risk of accidents. While the front glare is direct, rear high beams reflect into the driver’s eyes via mirrors. Solutions like polarized rearview mirrors help to some extent by adjusting the angle of light reflection. Some vehicles, like Tesla, avoid using manual polarized mirrors and instead rely on other technological solutions, such as autonomous driving systems.

Those who misuse high beams, either out of ignorance or deliberately, pose a safety risk. A friend once said, “High beams are meant to be used anytime,” showing he neither understood traffic regulations nor the discomfort caused by high beams. Driving a high-seated American truck, he likely didn’t experience the glaring impact of high beams. Similarly, some older drivers habitually turn on high beams at night, believing it improves their visibility, unaware of the dangers they impose. For instance, the opposing driver may lose control under the intense light, leading to accidents regardless of the direction of travel.

High beams indeed extend the visible range, much like standing tall provides a broader view. However, every advantage has its drawbacks. The existence of both low and high beams reflects their distinct purposes. Low beams illuminate nearby details, while high beams guide faster travel by lighting farther ahead. Both are indispensable for safety and should be used appropriately. Tesla’s autopilot system exemplifies this by automatically switching between the two based on real-time conditions.

In a previous blog, I discussed a vehicle equipped with sensors within its high beams. These sensors automatically dim the high beams when detecting oncoming vehicles and adjust the headlights’ direction based on turns. Such innovations enhance safety and convenience for nighttime drivers.

No matter how car designs evolve, headlights remain indispensable. They are the “eyes” of a vehicle, not only providing visibility for the driver but also serving as safety signals for others on the road. Incorporating more automated control features is crucial for safer driving. While headlights illuminate the road ahead, they should never blind others. Proper use of headlights is not just a technical skill but also a reflection of safety awareness and driving etiquette.