总有车友们说后视镜那条黑线到底是干嘛的？说实话小编在没接触汽车行业的时候是完全不懂的，也是出于好奇于是，今天就给大家科普一下
There are always riders who say what is the black line in the rearview mirror? To tell you the truth, Xiaobian didn't understand the automobile industry at all when he didn't contact with it. It was also out of curiosity, so I'll give you a popular science today
因为这种后视镜用的是双曲率镜片，也就一个镜片2种曲率，后视镜内侧的2/3镜片采用平面镜，外侧的1/3镜片采用凸面镜，中间就是这条黑线分隔以让驾驶员更好的看清后面的情况。
Because this kind of rear-view mirror uses hyperbolic lenses, that is to say, one lens has two kinds of curvature. The two-thirds of the lenses inside the rear-view mirror are flat mirrors, and the one-third of the lenses outside the rear-view mirror are convex mirrors. This black line is used in the middle to separate them, so that the driver can better see the situation behind.
1、平面镜部分用来观察车身侧面较近位置的情况。
1. The flat mirror part is used to observe the near position of the body side.
2、凸面镜部分用来观察车身侧面较远位置的情况，另外可以减少后视镜的盲区，转弯时视野扩大了两倍，几乎可以完全盲点。
2. Convex mirror is used to observe the far position of the side of the car body. In addition, it can reduce the blind area of the rear-view mirror. When turning, the field of vision is doubled, and the blind spot can be almost completely eliminated.
3、双曲率镜面技术原理：依据车型、驾驶员眼点位置与后视镜相对位置、视野要求三个要素，运用光学原理和数据方法，对车辆的前后左右不同视野角度选择不同的曲率半径，并平滑过渡。
3. The principle of hyperbolic mirror technology: according to the vehicle type, the driver's eye position and the relative position of the rearview mirror, and the field of vision requirements, using optical principles and data methods, different curvature radii are selected for the front, back, left and right different field of vision angles of the vehicle, and the smooth transition is achieved.
这样，能够在满足基本不失真的条件下进一步扩大视野、减少盲区，既满足了强制性标准，又解决了盲区问题。另外，在镜面的设计上采用分界线的办法来警示驾驶员变曲率面仅供观察车后大致情况。
In this way, we can further expand the field of vision and reduce the blind area under the condition of basically no distortion, which not only meets the national mandatory standards, but also solves the problem of blind area. In addition, in the design of the mirror, the dividing line method is used to warn the driver, and the variable curvature surface is only used to observe the general situation behind the car.
