Intermittent windshield wipers operate in timed intervals rather than constantly. This keeps a windshield clean in conditions of misting or very light rain. In these conditions, constant wiping dries the window, causing blades to stick and squeak as rubber drags across glass. Before intermittent wipers were invented, the solution was to turn the wipers on, let them wipe the windshield once or twice, then turn them off, repeating this process several times a minute.
Today, there are various models of intermittent wipers. Some models have pre-set intervals with a knob adjustment setting that can be clicked over to one of a few predetermined intervals. Other models feature a control knob that is rolled clockwise or counterclockwise, stretching or shortening the interval between wipes.
Intermittent windshield wipers improved upon standard wipers that have been evolving since the manual wiper designed and patented by Mary Anderson in 1903. As history tells it, Anderson, on a trip to New York, noted that streetcar drivers had to open their side windows in rainy weather to see out around the front windshield. Vowing to address the problem, her solution was a single wiper blade attached to a lever located conveniently inside the vehicle. The lever could be used to draw the blade across the window to remove rain and snow while remaining inside. By 1916, Anderson’s invention became standard equipment on all American cars.
Today’s windshield wiper systems are virtually trouble-free in most weather. Intermittent windshield wipers were invented by Robert Kearns (10 March 1927 - 9 February 2005), an Indiana man who saw an opportunity to improve on standard wipers. Kearns realized a need for wipers that would work on a delayed switch principle, and designed then patented this invention in 1967. He presented his idea to the three major US auto companies, Ford Motor Company, General Motors and Chrysler, but none took him up on his idea. Beginning in 1969, however, Ford began introducing models with this feature, and the other automobile manufacturers followed.
Kearns sued Ford in 1978 and Chrysler four years later for patent infringement, but justice was a long time coming, with the legal saga lasting nearly two decades. The inventor eventually ended up collecting $10.2 million US Dollars (USD) from Ford, and $18.7 million USD from Chrysler for what the courts termed to be “non-deliberate infringement.”