HP PAGEWIDE PRINTING TECHNOLOGY
As early as 1991, HP was experimenting with PageWide Print Technology. What they learned was that they were not capable of achieving the incredible speeds possible with such technology and also achieving the quality necessary to carry the HP brand. What did come out of this early research was what they had to invent to achieve both goals… breakthough speed and professional quality.
HP’s new PageWide Technology takes proven, advanced commercial printing technologies and scaled them down to a new class of printers and MFPs. They do this with a stationary printhead that spans the width of the paper passing under it and sprays four colors of Original HP Pigment Ink from 40,240 tiny nozzles. And they do this with controlled and uniform drop weight, speed and trajectory. These Pigment Inks provide controlled ink-paper interactions, sharp and crisp text, high color saturation and rapid drying. Automatic nozzle health sensing and active / passive nozzle substitution result in dependable print quality.
HP PIGMENT INKS
The basic elements of ink-based digital printing are colorants, the process for transferring colorant to the paper, and office papers. Colorants form the image on paper by reflecting light at specific wavelengths to produce distinct colors. Colorants can be made of dyes, pigments, or a mixture of both. Dyes are composed of individual molecules, whereas pigments are tiny colored particles whose diameter is about a wavelength of visible light. Pigments offer superior color saturation, black density, fade resistance, and smear resistance (for example, from water and highlighters) on office papers and coated brochure papers. In order to produce colorful graphics and images along with sharp, crisp lines and text, the colorant must remain at or very near the paper surface. If colorant moves across the surface or penetrates too deeply into the sheet, then lines and text won’t be sharp, blacks won’t be dark, and colors won’t be vivid. To achieve high print quality, colorants must rapidly immobilize in a thin surface layer immediately after they reach the paper.
Ink travels to the paper surface in tiny, 6 picoliter drops. There are one trillion (1,000,000,000,000) picoliters in a liter, and a gram of ink yields about 170 million 6 picoliter drops. The printhead ejects drops one at a time through individual nozzles, and each drop must emerge at a consistent weight, speed, and direction to place a correct-sized ink dot in the correct location. An HP Thermal Inkjet printhead has no moving parts. Nothing moves except the ink itself. Inside the printhead, an electrical pulse lasting about one microsecond—one millionth of a second—heats a tiny resistor in the drop generator—a three-sided chamber with a refill channel and nozzle—that is filled with ink. A thin layer of ink vaporizes to form a bubble that expands to propel a drop out of the nozzle at around 10 meters (33 feet) per second. The bubble acts like a tiny piston, rising out of the floor of the chamber to push ink through the nozzle overhead. As the bubble collapses, after about 10 microseconds, it breaks the ink stream into a droplet and draws fresh ink into the chamber refilling it for another cycle.
SCALABLE PRINT TECHNOLOGY
The dependable print quality, speed, and reliability of HP Officejet X Series printers is made possible by HP Scalable Printing Technology (SPT)—the latest generation of HP Thermal Inkjet technology that employs ultra-precise and proven materials, design rules, and manufacturing processes.
HP’s PageWide Technology uses a 4-color writing engine assembly. Ink cartridges for black,magenta, cyan, and yellow inks plug into ink fittings at the top of this assembly that provides pressure regulation and filtration for each ink. The writing engine assembly also senses when the cartridge is running low or out of ink. The printhead has 10 HP Thermal Inkjet chips, called dies, placed upon rigid, dimensionally stable, injection-molded plastic carriers. The carriers precisely align each die in the array and provide interfaces for the ink.
MANAGING 40,240 NOZZLES
HP PageWide Technology periodically tests the performance of all 42,240 nozzles on the printhead to help maintain dependable print quality, through the use optical sensors to calibrate the printhead, measure nozzle performance, and monitor paper motion.. This automatic process finds nozzles that are not performing within specifications, and also checks each nozzle frequently so that it catches and corrects any failures that could affect print quality. For HP Officejet X Series printers, HP developed a new technology called Backscatter Drop Detection (BDD). BDD employs innovative optics and multiple photodetectors along with advanced analog and digital signal processing. Unlike other optical methods, where a drop passes between a light source and a detector, BDD works by detecting the light that is backscattered (reflected) by a drop passing through a focused light beam. The Backscatter Drop Detector can test several hundred nozzles per second. HP Thermal Inkjet’s high drop rates and high nozzle density provide both active and passive nozzle substitution to suppress the effects of failed nozzles. This is one of the keys to the excellent print quality achieved by HP Officejet X Series printers.
Periodic printhead servicing is an essential part of reliable print quality. It keeps good nozzles working and may be able to recover bad ones. HP Officejet X Series printers feature a builtin service station cassette9 that performs four key functions: printhead capping, nozzle conditioning, nozzle plate wiping, and ink containment used for servicing. While printhead servicing is automatic, a user may initiate a printhead cleaning cycle, if required.
MOVING THE PAPER
To compete with color laser printers in small workteam environments, HP Officejet X Series printers need a compact, reliable paper transport that produces fast, face-down, correct order output with built-in duplexing. HP designed a new paper transport to meet the needs of pagewide array printing. The paper transport effectively stabilizes and constrains the sheet through the printer from pick to drop. It delivers reliable paper pick, low jam rates, and continuous and accurate movement of the paper in the print zone. Sheets are printed, duplexed, and delivered to the output tray without smearing ink.
BLAZING FAST PRINT
The data processing architecture for HP Officejet X Series printers was designed to support the high printing speeds from the pagewide printhead as well as provide fast first page out. Throughput of HP Officejet X Series printers in General Office and Professional (default) modes are shown in the table at left. First-page-out time—measured from the moment of selecting “Print” to the drop of the first page into the output tray—depends on a number of factors including host processor speed, interface type, network speed and network traffic, document complexity, and printer status (active, standby, sleep). From standby, HP Officejet Pro X Series printers take less than 10 seconds to put out an ISO standard page.
HP PageWide Technology breakthroughs enable the high performance and robust print quality of HP Officejet X Series printers. HP Officejet X Series printers offers the best of toner- and ink-based printing and delivers high levels of reliability, color and black print quality, and productivity. These printers offer low product acquisition costs, have low total energy consumption, and produce color pages at up to twice the speed and up to half the printing cost compared with color laser printers.