All windshields are not created equal, and that’s not just referring to size. The primary purposes of a windshield are to act as structural support for the roof, ensure proper airbag deployment, and protect passengers from the elements. In addition to these fundamental roles, there are other technologies offered by some auto makers that dramatically increase the usefulness of the windshield. We will look at a couple of these features in our first installment of “Advanced Windshield Features”.
Heated Windshields
In cold weather, one of our worst enemies is frost on the windshield. We’re typically stuck with one of three choices:
1) Start and warm the engine, and wait as the defroster slowly melts the ice;
2) Get out the trusty ice scraper and put your back into it; or
3) Splash warm or lukewarm water on the windshield. We can’t stress enough that this should never be done for two reasons. First, water splashed on the windshield can simply freeze while you try to clear the ice, and secondly because warm water on a freezing cold windshield can result in severe damage to the glass in the form of cracking.
Heated windshields were developed decades ago in order to make ice and snow removal much easier, and discourage buildup while driving in bad weather. A heating element is embedded in the windshield glass to create a similar effect to the rear defroster. Over the years heated windshields have fallen in and out of style, and they are still not a common feature. However there are modern vehicles still produced with heated windshield options, such as Land Rovers, Toyotas, and Lexus to name a few.
Because the heating element is directly embedded into the glass, moderate or severe damage may mean replacement of the entire windshield to ensure the heating feature continues to operate correctly.
Rain Sensors
Another popular feature on modern windshields is the rain sensor, which is a switching device that is activated by rainfall and automatically engages the vehicle’s windshield wipers. The technology finds its original roots from back in the 1950s when Cadillac began experimenting with a water-sensitive switch that would automatically close the convertible top and raise open windows of a vehicle.
The most common implementation of this technology is based on “total internal reflection” – an infrared light is directed onto the windshield from the interior at a 45 degree angle which eventually reaches a sensor that measures the reflected light. When the glass is wet, less infrared light is able to reach the sensor, which will then activate the wiper blades automatically and adjust their speed depending on the amount of water making contact with the glass. Vehicles with this feature still allow the driver to use the wipers manually, with a separate option for automatic wipers.
