An accidental touch with a soldering iron created the inkjet printer
In 1977, Canon engineer Ichiro Endo was experimenting with liquid ink when he accidentally rested a hot soldering iron against the needle of an ink syringe. The sudden heat instantly vaporized a microscopic layer of ink, creating an expanding vapor bubble that forcefully expelled a clean droplet from the needle tip. Recognizing the commercial potential of this thermal pulse, engineers developed thermal inkjet printing, which rapidly replaced noisy mechanical impact printers.
An Accidental Spark in Tokyo
In August 1977, an engineer named Ichiro Endo was working in a Canon research laboratory in Tokyo, exploring ways to control liquid ink using piezoelectric actuators. During an experiment, he inadvertently brought the hot tip of a soldering iron into contact with the needle of an ink-filled syringe. Rather than merely warming the metal, the sudden surge of heat caused a small volume of ink inside the needle tip to boil instantly. A microscopic vapor bubble expanded with rapid force, ejecting a small, clean droplet of ink out of the opening.
Endo immediately recognized the significance of what had happened. Ejecting fluids using mechanical pressure generated by piezoelectric components had long required intricate, delicate physical assemblies that were difficult and expensive to scale. The thermal reaction, by contrast, generated powerful hydraulic force purely through an electrical heat pulse, eliminating the need for complex moving parts at the nozzle tip. This sudden realization laid the foundation for what Canon would patent and brand as Bubble Jet technology.
Around the same time, researchers at Hewlett-Packard in the United States were independently exploring similar thermal concepts. Led by John Vaught and other engineers, HP was investigating ways to harness thin-film resistors to vaporize liquid and propel droplets. Both companies soon realized that thermal actuation could allow printheads to incorporate hundreds of microscopic nozzles on a single semiconductor wafer, opening the door to inexpensive, high-resolution digital printing.