Solid ink is a technology used in computer printers and multifunction devices originally credited with creation by Tektronix in 1986. After Xerox acquired the Tektronix Color Printing and Imaging Division in 2000, the solid ink technology became part of the Xerox line of office printing and imaging products. Early offerings focused on the graphic arts industry.
However, after a legal battle with Dataproducts Corporation, Tektronix ended up paying royalties to Dataproducts for the use of the technology.[why?]
The first solid ink printer, the SI-480, was developed and released to the market in 1988 by Dataproducts Corporation. This was a monochrome printer that met with limited success. The first color solid ink printer was also released by Dataproducts Corporation.[when?]
The Xerox Phaser III product introduced in 1991 cost $10,000 US. As the technology improved and costs were reduced, the focus shifted to office printing environments where quality and cost efficiency are important.
Solid ink printers are still expensive: Xerox remains the only producer.
In the 1990s, a succession of solid ink printers capable of printing up to Tabloid Extra size were introduced, including the Tektronix Phaser III, the Tektronix Phaser 300, and culminating with the Tektronix Phaser 380 in 1997.
As of July 2015, the Xerox ColorQube 8580 and Xerox ColorQube 8880 printers are the current solid ink printer models.
Solid ink technology utilizes solid ink sticks instead of the fluid ink or toner powder usually used in printers. Some types of solid ink printer use small spheres of solid ink, which are stored in a hopper before being transferred to the printing head by a worm gear. After the solid ink is loaded into the printing device, it is melted and used to produce images on paper in a process similar to offset printing. Xerox claims that solid ink printing produces more vibrant colors than other methods, is easier to use, can print on a wide range of media, and is more environmentally friendly due to reduced waste output. The sticks are non-toxic and safe to handle. In the mid-1990s, the president of Tektronix actually ate part of a stick of solid ink, demonstrating that they are safe to handle and presumably, eat. The medium of the ink was (at least at the time) made from food-grade processed vegetable oils.
Due to the way solid ink printers put the ink onto the page, print quality is considered to be excellent, with bright colors. Excellent results can be achieved with low-quality stock, as the wax covers the stock with a glossy, almost opaque, surface. Solid ink printers are able to print on many different types and thicknesses of media. They are much less sensitive to changes in media type than are color laser printers.
Because solid blocks of ink are used, there is less waste generated than is with laser printers or inkjet printers, which produce empty ink or toner cartridges, in addition to packaging and packing materials. A loose ink block does not leave any residual cartridge after it is consumed - only a crushable, thin, plastic packing tray and a recyclable cardboard packaging box.
Solid ink printers have an advantage over ink-jet printers for situations involving intermittent use with long periods of downtime. This is because melted solid ink that has subsequently cooled and re-solidified inside the ink-delivery pathways is a normal part of printer operation. So, this cooled-and-solidified ink does not dry out. And, while the printer is not operating, the solidified wax helps to prevent oxygen and moisture from interacting with many internal parts of the ink-delivery components.
Solid contaminants in ink blocks can clog printhead nozzles when using original or compatible inks, and may require costly printhead replacement. For this reason, many third-party ink manufacturers provide a guarantee and will pay for the replacement of a damaged printhead. Xerox also provides its own warranty.
When the device is cold, the first page may take several minutes to print. However, once the printer is warmed up, the time to print the first page is negligible.
The ink must be heated, and a large portion of the printing mechanism must be kept at or near the ink's melting point during use. When the printer is in "sleep mode", most units keep a small pool of each color wax within the printhead heated to a temperature just above the ink's "freeze point". According to the Xerox service manual, this consumes about 50 watts.
Every time the printer loses power for long enough to cause the portion of ink which was being kept above its "freeze point" in the printhead to drop below that temperature, the mass of ink in each reservoir would have contracted in size enough (as a result of the cooling) to permit air to enter the printhead, which would result in print aberrations until the printhead reservoirs had been refilled by the ink-melter assembly above it. As a result, the printhead is then purged using a vacuum pump, causing some ink to be flushed from the printhead's holding tanks into the waste tray to remove the air from the printhead. (Xerox printers have a "waste ink" tray for this purpose. Since all four inks are dumped into a unified "waste ink" tray, it is impossible to reuse the lost ink since the four process colors coalesce to form a single solid mass in the tray, which look much like solidified candle wax drippings, but almost black.) If the printer was in its sleep state, less time without power would be required to necessitate a purge cycle than if the printer was in its ready-to-print state (since the printhead is kept much hotter when ready-to-print).
The printer contains melted wax when at operating temperature, and owners' manuals warn that it cannot be moved until it has completed a special cool-down cycle selected from the machine's control panel. It is recommended to provide a 30-minute cool down time from the point of removing main power, however all modern solid-ink printers have a shutdown cycle which use fans to solidify the ink in less than ten minutes, with the added benefit of physically restraining the printhead to prevent damage during moving or shipping. The manuals warn that substantial damage is possible otherwise, requiring servicing by a trained technician if not properly cooled down before moving the printer. Moving the printer before cool down completes can damage the print head by spilling molten ink between reservoirs of different color as well as over other components inside the printer (motors, belts, etc.), and is not covered under maintenance or warranty. Because of the liquid-ink-spillage concern, solid-ink printers are not suitable for mobile usage, such as on movable carts for printing pricing tags in retail settings.
Unlike some inkjet printers where the cartridge includes the print head, the printhead in these printers is fixed. Over time, parts of the printhead may become permanently clogged, resulting in unsightly streaks, but there are printhead and drum cleaning cycles and jet-substitution options which can resolve most printing issues. There is a filter for the ingested ink implemented at least on the recent ColorQube devices (8570/8870), according to a service manual for those models. Dust caused by the use of cheap paper may cause printhead clogging, which is why Xerox recommends the use of papers that are not prone to giving off dust and fibers during regular usage. Paper dust may also accumulate as debris inside the printer; this could cause abrasions on the drum and may mimic a weak or missing jet. For this reason, the basic built-in drum-cleaning procedure is therefore recommended to be invoked at least three times before initiating printhead-nozzle cleaning cycle. The printhead system also contains a wiper-assembly unit that is used to wipe the printhead from dust, debris and residual ink, in order to protect the nozzles from clogging. Overall, the design of this system is robust: printheads have been known to last one million prints or more.
Ink blocks are not compatible between Phaser models, due to Xerox changing each CMYK molded shape with each new model release due to changes in the formulation (and especially melt point) of the ink. Special openings prevent the insertion of ink sticks from the wrong model, or the wrong slot.
Lamination becomes difficult due to the nature of the ink technology. The ink melts and becomes smeared unless the laminator temperature is reduced to just enough to seal a pouch.
- 380 DSE (PDF), Xerox.
- Solid Ink, Xerox.
- Jaeger, C. Wayne, Color Solid Ink Printing — How does a solid ink printer work?, Xerox Corporation, retrieved 2009-09-20.