# How Intermittent Windshield Wipers Work > Robert Kearns' 1967 patent for the first electronic intermittent windshield wiper system that mimics the human eye's blinking motion. - **Patent:** US 3351836 - **Original title:** Windshield wiper system with intermittent operation - **Owner:** TANN CO - **Granted:** 1967 - **Status:** Public domain (expired) - **Times cited:** 23 - **Field:** automotive, mechanical ## What it does This patent describes an electronic control circuit for windshield wipers that introduces a pause between each wipe. It uses a transistor to act as a switch that cuts power to the wiper motor at the end of a cycle. A capacitive timing circuit then holds the motor off for a set duration before triggering the next cycle. A mechanical switch linked to the motor's position ensures the wipers always return to the bottom of the windshield before the pause begins. ## What it does NOT cover - Does not cover purely mechanical or vacuum-based intermittent wiper systems. - Does not cover systems that adjust wipe speed based on rain sensors or optical detection. - Does not cover continuous-speed wiper systems that lack a dwell period. ## The clever bit The innovation lies in using a capacitor to create a variable time delay that controls a transistor, allowing the motor to 'rest' at the bottom of its arc rather than running continuously. ## Real-world examples 1. Standard intermittent wiper settings on almost every car manufactured since the 1970s. 2. The 'delay' setting on automotive wiper stalks. ## Why it matters This invention solved the problem of driving in light rain, where constant wiping creates annoying noise and smears the windshield. It became the subject of one of the most famous patent infringement cases in history, pitting the inventor, Robert Kearns, against major automotive manufacturers who adopted his technology without licensing it. ## Frequently asked questions ### What does How Intermittent Windshield Wipers Work cover? Robert Kearns' 1967 patent for the first electronic intermittent windshield wiper system that mimics the human eye's blinking motion. ### Who owns patent US 3351836? TANN CO owns this patent, granted in 1967. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 3351836 cited by? This patent has been cited by 23 later patents that build on its ideas. ### What problem does this patent solve? This invention solved the problem of driving in light rain, where constant wiping creates annoying noise and smears the windshield. It became the subject of one of the most famous patent infringement cases in history, pitting the inventor, Robert Kearns, against major automotive manufacturers who adopted his technology without licensing it. ### What does this patent NOT cover? Does not cover purely mechanical or vacuum-based intermittent wiper systems. **Full plain-English explainer:** https://patentbrief.org/patent/us/3351836/intermittent-windshield-wiper-kearns **Original patent:** https://patents.google.com/patent/US3351836 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Mary Anderson Invented the Windshield Wiper](https://patentbrief.org/patent/us/743801/windshield-wiper-anderson) — A 1903 invention by Mary Anderson that allowed drivers to manually clear rain and snow from their windshields using a lever inside the vehicle. - [Ralph Teetor's Speed Control Device for Automobiles](https://patentbrief.org/patent/us/2519859/cruise-control-teetor) — A 1948 invention by Ralph Teetor that introduced the mechanical foundation for modern cruise control by creating a system to resist accelerator pedal movement at a set speed. - [How Touchscreens Save Battery by Sleeping Between Touches](https://patentbrief.org/patent/us/8125456/multi-touch-capacitive-scanning) — A power-saving method for touchscreens that puts the main processor to sleep when not in use and wakes it up only when a touch is detected. - [How the First Automatic Pop-Up Toaster Works](https://patentbrief.org/patent/us/1394450/pop-up-toaster-strite) — Charles Strite's 1921 patent for the first toaster that automatically pops bread up after a set time, preventing it from burning. - [How Robert Moog Used Transistors to Shape Synthesizer Sounds](https://patentbrief.org/patent/us/3475623/moog-synthesizer-ladder-filter) — A 1969 invention by Robert Moog that uses the internal resistance of transistors to create the iconic filters that define the sound of analog synthesizers.