US 4,345,262 · Granted 1982-08-17

Canon's 1982 Ink Jet Breakthrough That Revolutionized Home Printing

Imagine a tiny heater that zaps ink so fast it explodes into a perfect mist of droplets, spraying onto paper at precise angles. That's what Canon patented here—a method for controlling electrical pulses to heat ink and fire it out like a microscopic cannon, creating sharp printed images without needing ribbons or mess.

Curated and verified by the IsItPatented Editorial team

The plain-English version

What it protects

The claim covers a specific method for shooting ink droplets onto paper using an electro-thermal transducer (a heating element) triggered by carefully timed electrical pulses. What's protected here is the combination of: using pulse widths between 0.1 and 500 microseconds, spacing those pulses so the wait time is at least three times longer than the pulse itself, and using that rhythm to heat ink in a chamber until it sprays out as fine droplets. Anyone making a printer that uses this exact timing and heating approach would potentially infringe.

Why it matters

This patent became foundational to Canon's ink jet printer business, which grew to dominate consumer and office printing for decades. By locking down the precise electrical control method for heating and ejecting ink, Canon created a competitive moat that other manufacturers had to design around. Ink jet printing eventually became cheaper and more practical than laser printing for home use, and this patent helped establish Canon's leadership in that market from the early 1980s onward.

Real-world use

Every time someone prints a photo or homework assignment on a Canon ink jet printer, millions of tiny ink droplets are being fired at the paper using the rhythm and heating method this patent describes.

Original USPTO abstract

An ink jet recording method which comprises contacting or bringing closer an electro-thermal transducer with or to a recording liquid in an operating chamber having a discharge orifice, introducing into the electrothermal transducer an input pulse signal with its pulse width being in a range of from 0.1 mu sec. to 500 mu sec., said input pulse signal being introduced in such a manner that its input cycle becomes at least three times as large as said pulse width, discharging and sputtering said recording liquid from said discharge orifice in the form of fine droplet in accordance with operating force developed within said operating chamber, and effecting image recording on the surface of a recording medium with the liquid droplets.

Patent details

Publication number: US 4,345,262
Filing date: 1980-02-07
Grant date: 1982-08-17
Assignee: Canon Kabushiki Kaisha
Inventor(s): SHIRATO; YOSHIAKI, TAKATORI; YASUSHI, HARA; TOSHITAMI, NISHIMURA; YUKUO, TAKAHASHI; MICHIKO
CPC class: B41J2/0458

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