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How Do Windshield Rain Sensors Work?


There are many comfort options on a car that you can get used to very fast: one of these is the auto rain sensor. The equipment provides improved control over a car’s wipers, which depends on how dense the rain is. It helps to make driving in the rain easier since it helps you focus your attention better on the road instead of the rain.

A rain sensor allows you to perfectly control the wipers’ operation. The intermittent setting normally should adapt constantly to the rain’s density, and quite often wipers are left on for quite a long time after the rain has ended.

These problems are overcome by automatic wiping and allow you to do the following things:

Automatically starts the wiper function
Adapts the wiping speed to the specific atmospheric conditions
Other functions are associated like automatic closing of electric windows, roof, etc.

Auto rain sensor advantages

The detector lets you focus all of your attention on driving your car. It is quite reactive (reaction time of 0.1 seconds) and is able to detect sudden splashes coming from other cars. Overall, it helps to improve your driving safety and comfort.

A rain detector system is comprised of these elements:

A calculator which manages the rain detector’s wiping system. It adapts the wiping rate according to the rain density and potentially controls other auxiliary functions, like lighting or closing openings.

A rain sensor is placed on the windshield inside the mirror’s pedestal.

According to the rain’s intensity, a variable electrical signal is sent out by the sensor to the computer. Then it controls the wiping and scanning speed proportionally.

The infrared sensor

This sensor is comprised of two diodes, with one receiving an infrared ray and the other one transmitting one. This beam gets diffused in the windshield’s glass. In dry weather, the walls reflect it to the receiving diode. This system is passive. When it is raining, drops of water that are on the windshield’s surface deflects the light beams and absorbs it: there is no photodiode supplied any longer, and the wiping is triggered by the system. The sensor is light sensitive and enables the “automatic lighting” function: it is able to switch the headlights on automatically in the event there is loss of light: tunnel, night, etc.

The ultrasonic sensor

Ultrasound technology is used by this variant. It has a similar principle but isn’t sensitive to light. It also doesn’t enable automatic light function. Ultrasound and infra-red both are undetectable to the human eye, and they don’t interfere with any of your behavior.

Original equipment

When you buy a new car, all brands now offer the “automatic wiping” option. Builders estimate the extra cost to be $150 to $300.

Adapting an “auto rain detector” kit

Fitting a kit onto your vehicle is possible. The product usually offers two cumulative functions which are “automatic lighting” and “automatic wiping.” These types of kits cost ranges from $70 to $90.

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