What is the function of the black dot on the rearview mirror installed in the car?
On the edge of the rearview mirror installed inside the car there is usually a small black dot, not many people know what its function is.
New cars today are often equipped with many technologies and features by manufacturers. One of them is the small black dot on the upper edge or the button on the lower edge of the rearview mirror installed inside the car.
This is a detail of the automatic anti-glare system of the rearview mirror installed inside the car.
This feature is designed by car manufacturers to support drivers in cases where light reflects from the car behind, causing glare to the driver. Accordingly, on cars equipped with auto-dimming rearview mirrors, there will be two light sensors. The first is mounted on the back of the glass to automatically detect light conditions in the dark or at night.
The front sensor - usually designed as a small black dot on the top edge of the mirror - will measure the amount of light emitted from the rear of the car, such as the headlights of vehicles behind, then adjust the light intensity on the rearview mirror accordingly to assist the driver in observing.
In addition, some types of auto-dimming rearview mirrors commonly found on Japanese car models are designed with a button to activate the auto-dimming feature on the lower edge of the rearview mirror.
For car models that are usually equipped with rearview mirrors installed inside the car but do not have an automatic anti-glare feature (usually on popular car models), the manufacturer will design a small lever behind the glass. When being dazzled by the headlights of vehicles behind or the environmental lighting conditions, the driver just needs to push the small lever behind the mirror down and adjust the mirror angle to suit the viewing range for use.
