US 4,463,359 · Granted 1984-07-31

The Bubble-Jet Patent That Launched Canon's Printer Revolution

Canon figured out how to shoot tiny droplets of ink onto paper by creating and collapsing bubbles inside a microscopic chamber. Instead of letting the bubble shrivel unevenly (which would mess up the next shot), they designed it to contract smoothly, so the printer could keep firing perfectly aligned drops over and over.

Curated and verified by the IsItPatented Editorial team

The plain-English version

What it protects

The claim covers a method and apparatus for emitting liquid droplets from a small orifice by generating a bubble in a liquid chamber and then allowing that bubble to contract gradually rather than collapse suddenly. What's protected here is specifically the controlled, smooth contraction process that prevents the orifice from receding too far into the chamber—a key technical detail that makes reliable, repeatable droplet ejection possible. The patent also protects the staggered arrangement of multiple emission heads and the time-division drive circuitry used to control them.

Why it matters

This patent represents a foundational breakthrough in thermal inkjet printing technology. By solving the mechanical problem of consistent droplet generation through controlled bubble behavior, Canon created a reliable, high-speed printing method that became the dominant technology in consumer and commercial printers for decades. The invention's emphasis on precise bubble contraction and multi-head staggered arrangements enabled the compact, affordable printers that became standard office equipment worldwide.

Real-world use

Every time an inkjet printer fires dots onto a page, it's using this bubble-jet principle—heat pulses create and collapse microscopic bubbles to propel ink with precision, thousands of times per second.

Original USPTO abstract

This invention provides a method of and apparatus for emitting a droplet from an orifice by generating a bubble in a small liquid chamber in response to a droplet generating instruction. The method and apparatus are particularly characterized having gradual contraction of the bubble to prevent excessive recession of the orifice in the liquid chamber which recession would hinder subsequent droplet generation. For achieving the above-mentioned functions the droplet generating apparatus, or the droplet emitting head, is provided with a structure which allows effective generation and annihilation of the bubble. The present invention also provides a novel apparatus having emission heads in a staggered block arrangement for improving alignment density of the devices and elements and time-division drive circuitry.

Patent details

Publication number: US 4,463,359
Filing date: 1980-03-24
Grant date: 1984-07-31
Assignee: Canon Kabushiki Kaisha
Inventor(s): AYATA; NAOKI, SHIRATO; YOSHIAKI, TAKATORI; YASUSHI, SEKI; MITSUAKI
CPC class: H04N1/40031

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