Inkjet technology

Inkjet technology originally was invented for depositing aqueous inks on paper in 'selective' positions based on the ink properties only. Inkjet nozzles and inks were designed together and the inkjet performance was based on a design. It was used as a data recorder in the early 1950s,^[1] later in the 1950s co-solvent-based inks in the publishing industry were seen for text and images, then solvent-based inks appeared in industrial marking on specialized surfaces and in the 1990's phase change or hot-melt ink^[1] has become a popular with images and digital fabrication^[2] of electronic and mechanical devices, especially jewelry.^[2] Although the terms "jetting", "inkjet technology" and "inkjet printing", are commonly used interchangeably, inkjet printing usually refers to the publishing industry, used for printing graphical content, while industrial jetting usually refers to general purpose fabrication via material particle deposition.

Many companies have worked with inkjet over the years. Many patents have been issued and the technology has been used in a number of products. The basic form of the inkjet was a single nozzle with either fluid forced through under pressure, pulled from it by electrical potential or pushed out with the help of a piezo. Single nozzle inkjets will be discussed first in this introduction. Inkjet technology was pioneered by Teletype Corporation^[3] in the 1960s which introduced the "electronic pull", high voltage drop extraction from a nozzle, Inktronic Teleprinter in 1965 printing at 120 characters per second (cps) from a row of 40 inkjets using the Charles R. Winston patent, Method and Apparatus for Transferring Inks, 1962, US3,060,429. Teletype experimented with "hot-melt" wax inks as described in a Teletype patent by Johannes F. Gottwald, Liquid Metal Recorder, 1971, US 3,596,285, that outputs a fabricated metal symbol (Stock exchange symbols and quotes) able to be removed from the conveyor carrier and the Bismuth metal alloy reused if desired. The use of Hot-melt inks with a newer Drop-On-Demand inkjet technology(invented by Zoltan in 1972) with these inks would not be seen again until 1984 at Howtek and Exxon.^[3]

Howtek was started as R.H Research in 1982 by Robert Howard after successfully growing Centronics,^[3][4] the first dot-matrix solenoid-driven wire ribbon impact printer company in 1968. Howard calculated his solenoid matrix printer^[3] was 10-20 times faster than Teletype. Howard had tested making dots on paper by using ultrasonic sound in the late 1960s but did not advance the idea until some 20 years later in 1984 with Howtek when he hired 6 key employees from Exxon to develop his hot-melt color inkjet printer idea..

Exxon Office Systems(EOS), Brookfield, Ct plunged into the non-impact printer business in the late 1970s and invested as much as $2 billion.^[3] Patent records show a lengthy list of printing background employees at the EOS, Exxon Enterprises, Danbury Systems Division starting in 1978 including Ken Bower who was recruited by Exxon to found the engineering department at Exxon Enterprises. Ken's first job out of college in 1963 was at AT&T's Teletype, Division in Skokie, IL where his job was to transition an electro-mechanical stock exchange ticker (inkjet printer) into production. On his first day of work he smelled wax and was shown a 42 jet printer with heated printheads that was under development. Ken went on to work at UARCO business forms and made associations with developers of On-Demand inkjet, including Steve Zoltan at Gould and Silonics under Ed Kyser and Stephen Sears. Steve Zoltan was using the cylindrical piezoelectric tube with cylindrical compression and Ed Keyser was using a flat piezoelectric diaphragm that squirted ink like an oil can.

Two employees hired at Exxon (EOS) with no experience in printing were James McMahon and Kathy Olson. McMahon was hired to install the first Zoltan style single-nozzle inkjet, code name "Alpha Jet" to a fax printer and Olson was hired to build the "Alpha" jets for fax printer production. McMahon and Olson (married name McMahon) were two of the six employees^[4] hired by Robert Howard to design and build on-demand inkjets for the Pixelmaster color printer. Within 6 months of joining R.H Research(name changed to Howtek) the Alpha jet print samples with hot-melt ink were being shown at COMDEX, in Las Vegas.^[4] J. McMahon is credited with an Improved Inkjet System using the Zoltan technology at EOS and K. McMahon is credited with nozzle manufacturing techniques at Howtek. J. McMahon went on to work at Sanders Prototype(Solidscape) 3D printer manufacturer and is now employed at Layer Grown Model Technology supporting On-demand single-nozzle inkjets and claims to be the godfather of 3D Inkjet single-nozzle technology as a historian who worked in the field since 1978 with Steve Zoltan and Ken Bower at Exxon. 3D Inkjet single-nozzle printing has a direct path from Teletype hot-melt inks (Wax and metal alloy) to Steve Zoltan's single-nozzle jetting technology that never developed at Exxon with glass nozzles but became reality at Howtek with Teflon molded nozzles and heated printheads in 1984. An ex-Howtek employee, Richard Helinski is credited for the patent using two materials to produce particle deposition articles in 3D using Howtek style inkjets and thermoplastic inks. These same Howtek inkjets and materials were used in the Ballistic Particle Manufacturing, Personal Modeler and the Visual Impact Corporation, Sculptor 3D printer businesses that have since closed. These printers and original Howtek style inkjets and materials can be seen at the 3D Inkjet Collection in New Hampshire, the only historical collection of Zoltan style inkjets and 3D printers. Single nozzle jets are still in use today in Solidscape 3D printers and are considered to produce a very high quality model.