TCPglobal - news, views and issues on total cost of printing

Issue #0632/2 - Inkjet technology has come of age with the development of page-width printheads using Hewlett-Packard’s Scalable Printing Technology.

After years of saying that the technology is not right for a page-width inkjet printhead, and that it would be too expensive, the time has now come when Hewlett-Packard’s technology is right and fast corporate inkjet printing can become a reality.

Although there is no information yet available on any printers that will make use of the new developments, Hewlett-Packard has announced that its Scalable Printing Technology (SPT) is being scaled to benefit the enterprise – rather earlier than expected.

Inkjet printing has, to date, permeated the office, including the enterprise, largely from the point of view of providing low entry-cost personal printing. Often this takes the form of a back door purchase rather than a purchase through official purchasing channels. Consumables then tend to be acquired through the office supplies budget or via personal expenses. The result has been that formal accounting for the printing expense has been impossible.

Small, personal inkjet printing will not be affected by this new announcement. The new technology is an added feature, not a replacement feature, and will impact mainly at a corporate department level. If there is any threat involved anywhere along the line, it is a threat to laser technology not to inkjet technology.

So, the purpose of this article is to take another look at Scalable Printing Technology, why this opportunity has arisen and what the potential is for application of the technology.

Scalable Printing Technology

Already in use in a number of Hewlett-Packard’s single function desktop and All-in-One inkjet printers launched since summer 2005, like the Photosmart 3310, the Photosmart B9180 professional photo printer and the recently launched Photosmart Express Station retail photo kiosk, SPT is not a brand new technology. The configuration used in the Photosmart Express Station is the forerunner to the configurations we are now looking forward to for the office environment.

At 4.25 inches wide (108mm), the static printhead used in that device is around four times the size of any previous generation inkjet printheads. Each head has a massive 10,560 nozzles (5,280 per colour), which means that the three printheads required to drive the unit (two colours per head) are capable of firing not far short of a billion ink drops per second (maintaining the Moore’s Law progression for inkjet printheads) – and at a native resolution of 1,200dpi!

Thanks to the flexibility of Hewlett-Packard’s manufacturing process, photolithography, which allows far great accuracy (sub-micron) of nozzle positioning, inkjet printheads to service almost any printer can be made.

A glance at this photo of the printhead instantly reveals the potential for printheads to be built to almost any width required. In this instance, the head comprises five component head units, each spanning approximately 0.875inch (22mm) - the size of the printhead used in the latest range of desktop printers.

To create each of these component printheads, whereas traditional printhead manufacturing processes require the head to be fabricated in several ‘slices’ using a process similar to the fabrication of silicon processor chips, the photolithographic process allows a fully integrated layer to be created that includes both nozzles and ink channels together.

Thus, instead of being a multi-layer construction that relies on accurate and faultless bonding, fewer pieces makes the SPT manufacturing process faster, more accurate and, eventually, less costly.

Further major advantage is gained from the fact that this single integrated layer can be much more accurately positioned over the heaters in the silicon substrate. If the nozzles are not accurately positioned over the heaters, the droplets will fire at an angle, meaning that drop positioning accuracy will be poor, especially where positioning is

inconsistent along a line of nozzles, and the image will suffer accordingly. SPT’s precise alignment of nozzles with heaters means that drops fire straight, landing where they are supposed to land.

Future developments of the manufacturing technology will certainly allow longer individual component printheads to be fabricated than is currently possible. This will permit ultra-wide head manufacturing with fewer component heads, thus again reducing manufacturing costs and with fewer alignment issues to face when combining those component heads.

Configuration – page-width printhead

So, on the basis that five component heads create a 4.25 inch print head, it only needs a 10-head configuration to allow full A4 printing in a single swath. We have constructed a simulation of what the head could look like in a 10-head configuration for A4 page-width printing – and, I would expect A3 format heads to be available very shortly, if not at the same time.

Primarily, the benefit of a page-width printhead is that the paper moves under the printhead instead of the printhead moving back and forth over the paper (as well as the paper under the printhead!). What this means is that the flow of paper through the machine is smooth and at a constant speed. There is no jerking, no potential for image registration to be compromised by that jerking and no image quality implications arising from the head moving in two directions.

These image quality implications include horizontal gaps, horizontal lines and horizontal bands, with the requirement for a multi-pass approach to guarantee a satisfactory image.

Horizontal gaps in traditional single-pass inkjet printing are caused when the paper is moved a fraction too much for the swath printed by the printhead. If the paper is moved 22.1mm when the head in use has a 22mm swath, a white gap of 0.1mm will be left in the image. Likewise, the opposite, a dark line can be printed when there is an overlap caused by the paper not being advanced enough for the printhead.

Banding is caused by the bi-directional movement of the printhead in traditional single-pass inkjet printing. Cyan ink placed on the page before the Magenta will produce a different colour to Magenta being placed before the Cyan. The result is a noticeable difference in colour between the bands of the image printed by the printhead moving in each direction.

This is overcome by using two-pass (or four-pass) printing so that there is ink laid onto every swath from both passes of the head. If half the droplets are laid down during the first path with Magenta laid on top of Cyan, by the time the second pass does the reverse with the other half of the droplets, the image will appear consistent.

However, the huge benefit of this type and size of printhead is the very fact that, with a native resolution of 1,200dpi, it allows the printhead itself to remain stationary while the media moves beneath it – meaning that print speed is vastly increased. No longer do we need to talk in terms of quoted print speed at draft print quality but we can move to quoting at full page-printer letter quality, matching the quality of laser printers.

One would assume that a high speed inkjet page printer of this nature will be constructed with a paper transport mechanism that is similar, if not identical, to a laser printer. Nevertheless, the system as a whole will still contain fewer moving parts, making it simpler and cheaper to produce and more cost efficient.

Hardware implications

So – no longer is inkjet a differentiator of printer categories. Inkjet printers now truly join the page printer category and the distinction will have to be made between page printers and moving head inkjet printers – perhaps along the lines of the true description for what we know as dot matrix printers, Serial Impact Dot Matrix (SIDM).

We can certainly look forward to single function and multifunction page printer products from Hewlett-Packard using the new SPT page-width inkjet technology. This puts Ricoh’s use of Gelsprinter technology in an MFP firmly into the shade.

There is absolutely no doubt that print speeds of 60ppm will be achievable from this technology. Perhaps the first iterations will not achieve 60ppm but, if not, we will see that speed very shortly and there is potential for speeds much faster than that.

Imagine the speed at which a printhead carriage in a current desktop inkjet printer moves across the page!

For a printer to print a page with a swath width of 22mm, as currently available from SPT printers, approximately 10 passes of the head would be required. A Hewlett-Packard printer outputting at letter quality using the 1,200dpi printhead will realistically be printing at a speed of around 6 to 8 ppm.

Taking a pessimistic 6ppm, that computes to an overall printhead speed of 22cm per second. Translate this into the paper movement under a page-width printhead and we can print a 29.7cm A4 sheet every 1.35 seconds (around 45ppm).

Allowing for the fact that there is no printhead to decelerate, stop, put into reverse and accelerate at the end of every pass across the paper, if we assume that a speed increase of up to 20% is possible with the page-width head, then we have a print speed of 55ppm.

Following this theory through to a logical next step, in an A3 configuration, a basic A4 print speed of 60ppm (one 21cm page per second) is achievable and the constant movement of the paper, instead of cross-page head tracking, should push that up to 72ppm.

Thus, there is probably no reason why we should not be in a position to expect 90ppm A3 inkjet MFPs from Hewlett-Packard in the fullness of time.

Hopefully, Hewlett-Packard will have taken a leaf out of Ricoh’s book and utilised an electrostatic paper transport belt, as used in many colour laser printers, to keep the paper firmly positioned during printing. At these speeds, it will be needed.

But, don’t forget that these machines will also be capable of producing the full glossy photo quality that Hewlett-Packard is renowned for.

Other benefits will include the fact that, if the product design is approached intelligently, the inks could potentially be replenished while the device is actually printing because the tanks have to be off-axis and could therefore be made accessible.

Cleaning of the printheads may be an issue periodically but this is unlikely to cause a serious delay in printing unless there is a serious nozzle problem requiring a deep clean.

One of the most important benefits of the use of this technology though, must be in the cost implications. Obviously, we are not in a position to make any cost calculations yet but the use of a very fast full colour print engine where cost can be measured in tens of Dollars rather than hundreds of Dollars will introduce volume colour printing and MFP capabilities to small businesses and small departments in a way never before possible.

Hewlett-Packard’s costing on the OfficeJet Pro K550 already offers a nominal Cost of Printing at less than a penny (0.94 pence) per mono page and 4.64 pence for colour pages. This compares to a nominal cost of 1.25 pence and 6 pence for Hewlett-Packard’s 30ppm Colour LaserJet 4700 – a saving of 25% and 23% respectively.

Potentially, the SPT page-width engine should be able to offer customers even lower Cost of Printing than the Colour LaserJet 4700, perhaps saving customers as much as one-third of the cost per page printed, especially when combined with a lower purchase cost and rolled into a long-term Total Cost of Printing!

At this stage, this is all rather speculative. We must wait for the devices to be released to see exactly what offerings Hewlett-Packard has felt comfortable with as a first generation.

However, this must be viewed as a very exciting development in the world of office printing and one that takes both page printing and inkjet printing into a new era.

~End~

This entry was posted on Friday, October 27th, 2006 at 12:02 am and is filed under Hardware, New Products, News, Total Cost of Printing. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.