Steve Temple, patent saint of inkjets

Next time you’re filling up your car at a petrol station, look down. If you see the manhole covers that the tanker drivers use, chances are that they were made using a 3D glass fibre weaving technique invented by Steve Temple, better known as the technical director of Xaar, Cambridge’s pioneering printhead developer. Xaar’s piezo-electric heads are used worldwide in wide format, industrial and office printers. Last month Xaar’s innovative new printhead factory in Huntingdon went into full production. Temple, one of the company’s founders in 1990, chose the same month to announce that he will be stepping down from the board in September. He’ll remain at Xaar for a few months to help to hand over to incoming research & development director Ramon Borrell, who has worked for HP since 1994. After that Temple will continue as a Xaar consultant and will also work on his own projects. So it was an opportune time to talk to him about the past four decades of inkjet development. He’s seen it all, and invented a fair amount of it.

At the end of the 1960s Temple was a young scientist working for Cambridge Consultants Ltd (CCL), a company which existed then and now to undertake research and develop it into products or components for clients, or which could be licensed or spun off into companies. Temple, an engineering graduate from Oxford University, was actually developing new technologies for the declining UK textile machinery industry, which saw automation as a possible answer to rampant overseas competition. His project in 1968 was a carpet making machine with textile-weaving potential. At the same time David Paton, a Cambridge engineering graduate, ten years older and with a couple of MBAs, was working on early ideas for digital printers. “The first experiments in inkjet at CCL were in 1969 when a colleague became excited about the possibilities of computerised printing,” Temple recalls. “David took up the challenge and by dint of much research, analysis and invention, came up with the fundamentals of his ‘Multijet Continuous Ink Jet,’ in which regular streams of tiny droplets the size of a human hair are steered either into a gutter or on to pre-selected locations on the print surface to print full width patterns on fabrics at commercially useful speeds.

“This was a startlingly accurate prediction of a future market need, about 30 years ahead of its time! This was typical of the man, in that the whole idea was founded upon theoretical concepts, some of which stretched back to Lord Rayleigh at the Cavendish Laboratory in the 1870s, and all of which were worked out on paper long before any actual models were made.”

This continuous flow printer used 20 jets in a circular array, firing 20 different binary colours (ie no tones). It worked particularly well as a textile printer, Temple says. “We sold this to ICI in Manchester. We actually made contact via a mis-addressed letter that reached the wrong Dr Smith and he was at ICI! Within a month we had a contract with ICI to build the first fabric printer. It ran at 2 m per second, 100 dpi, with 20 colours. But we had no idea how to control it. ICI wanted to develop it for wallpaper printing as well as textiles to spread the costs, but eventually it dropped it because the quality wasn’t good enough for wallpaper. CCL bought back the rights for around £10,000. That was the origin of inkjets at Cambridge Consultants.”

Cambridge Consultants became a powerhouse for inkjet development throughout the 1970s and 1980s, concentrating on the continuous flow inkjets that were best suited to industrial marking. “We actually invented bubblejets too, and rejected them!” recalls Temple. “Possibly rightly so, as we wanted production-scale printers and there are still no bubblejets doing this.” Some of the biggest names in industrial inkjet manufacture were spun off from Cambridge Consultants, including Domino Printing Sciences, Elmjet, Willett International and Linx Printing Technologies in the UK; Trident and Moore Business Forms in the USA; Imaje in France; and finally, in 2000, Inca Digital in the UK. “This has populated the world with ex-CCL inkjet experts,” Temple says. “Other companies’ technologies were more in-house, so they are not so widespread.” CCL and its offshoots weren’t the only inkjet pioneers of course. Siemens created a basic inkjet for scientific instrument recording in 1951. In 1966 Dr Carl Hellmuth Hertz at Lund University in Sweden patented a continuous- flow inkjet that allowed variable-intensity printing, originally for the medical ultrasound imaging he also invented. A developed Hertz concept was licensed by Iris in the 1980s to make photo-quality printers.

Scitex bought Iris in 1990 and developed a very effective series of proofers. DuPont also used Hertz-licensed technology in its successful Digital Cromalin proofers. Mead Digital Systems in the USA developed continuous flow technology of its own from 1972. Kodak bought this and renamed it Diconix in 1983, whose direct descendent (after a period in Scitex ownership) is today’s Kodak Versamark operation. Its single-pass mono and colour continuous flow inkjet presses are notable for very high speeds but modest image quality. In 1978 Canon and Hewlett-Packard independently both invented the thermal printhead technology that Canon calls BubbleJet, and cross-licensed the technology to each other. The major achievement of Canon and HP was to create desktop office and consumer inkjets, a major feat of engineering that made them small and affordable, yet reliable and idiot-proof. Temple and Paton worked on different aspects of ink jets at CCL during the 1970s, often co-operating. “CCL worked by a lot of informal brainstorming and sparring,” Temple recalls. “I tended to concentrate on the numerical side and calculations and David was good at the physics. But it was not until the 1980s that we decided to cooperate directly on drop-on-demand, and that gave rise to the Xaar technology. David had invented acoustic wave firing in 1980 before anyone knew how to build it.”

Temple contributed to the new jetting system in general, but his particular contribution was creating the shared wall between the jets. “Spectra and Xaar independently invented piezo electric, using shear mode that avoids the stresses of direct mode”, Temple explains. “It means you can get a lot of jets onto a small volume and they do not interact.”

Paton and Temple were founder-directors of Xaar in 1990, which despite a few financial blips and takeover rumours has remained a real success story for modern British industry. Sadly, Paton died in 1997. “We worked with a US company originally, which then gave up. Xaar was set up by venture capital and bought back the rights. We then licensed the technology to several Japanese manufacturers such as Toshiba Tec, Konica Minolta and Seiko Print. Today we reckon we cover more paper annually than HP, in terms of the tonnage going through Xaar based printers.”

Epson, although also part of the Seiko empire, developed its own piezo heads independently, leading to today’s successful Stylus range from desktop to wide format, and a lot of Epson heads in third party printers. Spectra remains Xaar’s most direct rival. Last year Fuji Photo Film bought Dimatix, Spectra’s US owner. Temple, as technical director, has overseen Xaar’s product development, which has led to some 90 patents for the company. Most recently he invented Xaar’s innovative Hybrid Side-Shooter (HSS) technology, an advanced print head that’s inherently resistant to blocking. This has taken ten years’ development but is now available as the Xaar 1001 ‘Platform 3’ head (Platform 1 heads are binary and Platform 2 are greyscale). HSS technology has great potential for high quality page-wide arrays in future single-pass printers, Temple say, as blocked nozzles are currently a limiting factor for drop-on-demand designs. HSS also has the interesting ability to jet really large particles, including metals for electronic circuits or decorative printing, as well as the up-and-coming areas of materials deposition for printable 3D structures with applications in engineering, manufacturing and medicine.

Temple stresses that he’s not retiring yet. “I’ve just turned 60, so I’ve another five years to retirement. I want to do another project, perhaps materials deposition. It’s an exciting field for inkjets and manufacturing in general. It’s an area I’d like to be involved in and I can continue to consult with Xaar and use HSS.”

This will also link neatly with Temple’s interests back to that 1960s loom. In the 1970s he adapted a 3D weaving technique first used on ancient Egyptian looms. He also explored producing woven plastics by focusing lasers into liquid acrylics. The glass fibre petrol station covers also arose from this interest in woven materials. “I’ll also be looking for new technologies to see if any fit Xaar in the long term. This will be looking at industries in general, not just print heads. But I think that materials deposition will be where it goes. So if you’re a printer who’s really gloomy that print-on-paper is going to be replaced by electronic displays, perhaps that’s an area to get into!” 

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