You can freely build on How Intermittent Windshield Wipers Work
This patent expired in 1984. Every claim — 1 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
TANN CO
Patent granted
1967
Expired
1984
Forward citations
23
What this patent covers
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 is now free to use
All 1 claims of US 3351836 are in the public domain. Specifically:
Claim 1: IN A WINDSHIELD CLEANING SYSTEM, AN ELECTRIC WINDSHIELD WIPER MOTOR UNIT FOR DRIVING WIPER MEANS THROUGH REPEATING WIPING CYCLES, AND CONTROL MEANS FOR AUTOMATICALLY DEENERGIZING SAID MOTOR NEAR THE END OF EACH WIPING CYCLE FOR A PREDETERMINED DWELL PERIOD, SAID CONTROL MEANS — 1 specific element
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
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.
Who is building on this today
The automotive industry at large adopted this fundamental logic. While the original patent has long expired, modern manufacturers like Ford, Toyota, and Volkswagen have evolved this into complex rain-sensing systems that build upon the basic timing logic established here.
Products built on expired version of this technology
Standard intermittent wiper settings on almost every car manufactured since the 1970s.
The 'delay' setting on automotive wiper stalks.
How to cite this patent in your documentation
TANN CO. US Patent 3351836. Windshield wiper system with intermittent operation. Granted 1967, expired 1984. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.