Issue #0523/2 - As Hewlett-Packard introduces its new Scalable Printer Technology, that offers speed, quality and efficiency benefits, the company looks forward to a bright future in the inkjet market.
In the annual review of ink jet printers from Hewlett-Packard, this year we are not seeing just a redesign or a revamp of existing technology, with marketing tweaks to make it more friendly or to add minor new usability features, or even to update the technology, but a radical new ink delivery technology for the company.
Hewlett-Packard’s ‘Scalable Printing Technology’ (SPT) is an inkjet printing architecture that allows the so-called ‘scaling’ of the ink delivery system for use in a wide range of applications including 6-ink photo printers (just launched in the PhotoSmart 8250), business oriented 4-ink devices and beyond.
Although not a new concept in the broadest sense of the word, because the outline configuration is based on a single permanent print head with separate and individual ink tanks (similar to that used in many Canon inkjet printers) the implementation is highly innovative. In particular, it incorporates technology that maximises ink usage, minimises ink wastage, ensures that air is economically removed from the system and prevents clogging of the print heads – even after long periods of inactivity.
Theoretically this means that a page is never wasted through faulty printing due to inactivity or because of lack of ink.
Making its debut in just the one printer at this point in time, the PhotoSmart 8250, the SPT architecture is designed so that it can form the basis of a wide variety of devices, both consumer and business oriented.
Whereas both Canon and Epson place individual ink tanks directly onto the print head, Hewlett-Packard has based its new SPT on the well-proven off-axis configuration used in its business inkjet and large format DesignJet printers over the last few years.
For the consumer photography products, this consists of six off-axis ink tanks located in a static position on a gantry structure that straddles the paper exit path. Ink is fed to the print head via a set of tubes that pass through a pump. Also in the system is a set of vent chambers that allows air to be separated from contaminated ink and for that ink to be collected for future use.
This is a critical element in the system because air can enter the system when changing ink tanks and the process of pumping ink can result in a froth developing in the ink within the system. In addition, inkjet print heads are susceptible to small amounts of air entering the system during extended periods of inactivity. Most inkjet systems remove the air bubbles and purge the contaminated ink by ejecting it through the nozzles – meaning wasted ink.
Not so the SPT! By sucking both ink and air bubbles from the printhead back through the vent chambers, and refilling the printhead with fresh ink, Hewlett-Packard is able to maintain the printhead without the wasteful priming and ink purging processes.
Although the SPT does not have its ink tanks on the printhead, Hewlett-Packard is using the well-tried technique of placing an ink reservoir on the print head. This means that there is always a supply of ink ready at the head and, because this reservoir is never allowed to run dry, the head is always primed and ready.
Drop-counting technology linked to the on-board reservoirs also ensures that Hewlett-Packard’s SPT knows whether there is enough ink available to complete the job in hand. Hence the situation is avoided where several £/€/$s-worth of ink and paper are wasted due to one colour running dry part way through the print. How many times have you spotted that one of your photos has developing ink-starved striping half way through printing?
If there is not enough ink available in the printhead reservoir to complete the job, the system enters its ‘recharge’ cycle – if any ink tank is empty as well, then the system will also ask for a new tank.
During the recharge cycle, ink is sucked out of the reservoir and is pumped back into the ink tanks. Then, fresh ink is pumped into the reservoir, ensuring that all colours are filled to the same level. Any excess ink and unwanted air is then sucked back out of the reservoir, through the vent chambers where the air is removed so that the ink can be reused.
As mentioned, this recharge cycle will activate when the drop counter indicates an ink-low status at the reservoir. In practice this means that it is activated between major print jobs and experience shows that it will certainly be activated after printing every full-page A4 photograph.
As the recharge cycle takes about 30 seconds, the process does have a negative effect on perceived print speed because, although the printer itself is fast, there is a delay between completing one A4 photograph and starting printing the next.
To put this in perspective, the printer is capable of printing an A4 borderless photo in one minute and 26 seconds, in comparison to six minutes on the PhotoSmart 7960 (No. 57/58 cartridges). However, once the 30 second recharge cycle is added, A4 images are printed at the rate of one every two minutes.
Even so, the new SPT printers should be producing A4 photos at about three times the speed of the PhotoSmart 7960! Impressive – and – the average speed for printing 10×15 borderless photos is about five-an-a-half times faster because, as long as the print job is not too long, the recharge cycle should wait till the end of the job.
CharisCo’s standard 12-image photo suite (www.charisco.com/photosuite) printed borderless on 10×15 media in just six minutes and 28 seconds – an average of 32 seconds each in comparison to 2 minutes 56 seconds on the PhotoSmart 7960! The recharge cycle kicked in at the end of the print run.
Source: HP R&DBecause the ink circulation system maintains the ink supply to the on-board tanks intelligently, and because the ink tanks are designed with a sump-style moulding at the bottom, it is able to use every last drop of ink contained in the tanks. There should never be any wastage and the amount of ink used in wiping and cleaning the nozzles should be extremely minimal.
For a machine of this nature – PhotoSmart 8250 – the tanks do seem rather small though. Containing only 4.5ml of ink in each of the colour tanks on delivery, aftermarket tanks contain between 3.5ml and 6ml of ink. A full black tank is supplied on delivery and aftermarket tanks are a reasonable capacity, at 17ml (a 6ml black tank is also available for low volume usage).
- Cyan, 4ml
- Magenta, 3.5ml
- Yellow, 6ml
- Photo Cyan, 5.5ml
- Photo Magenta, 5.5ml
Because yellow ink has a relatively low optical density, it may need to be used in greater volume to produce rich, full colour. Therefore, this is the colour provided in highest volume. By contrast, because magenta ink has the highest optical density, fewer drops are required to achieve the required density of image and hence is provided in the smallest quantity.
BUT – Hewlett-Packard makes mileage in its marketing literature that only the empty tanks need replacing at any one time, implying improved cost effectiveness.
This is Hewlett-Packard’s first venture into independent ink tanks for the consumer market and there are signs that this new system is very efficient. These factors would seem to have prompted a re-evaluation of the pricing methodology. Whereas the company could guarantee that users would have to buy a new tricolour cartridge when one ink ran dry, even if some ink was not used, now users will only need to buy a particular colour tank when that colour runs dry.
It is old news that the cost of printing is not contained in the actual ink – the physical cost of ink is almost negligible. With companies such as Hewlett-Packard spending billions of US Dollars developing ink writing systems, the real cost of printing is contained in the research and development.
Development of the Scalable Printing Technology cost $1.4bn and Hewlett-Packard recognises that the hardware itself is more expensive to produce than hardware that utilises integrated cartridges (less technology in the hardware). Hence, the manufacturer has to do a balancing act to ensure that adequate returns are achieved from ink sales to cover the technology investment in developing the ink and delivery system.
Therefore, because the tanks are now separate, Hewlett-Packard has to ensure that users will need to spend enough money on their printing to cover that cost. One way to achieve that is to ensure that users do not in fact gain extra pages because they are able to run every tank completely dry when in the past they would have been wasting some ink in two chambers of the tri-colour cartridge. The cynic would say that it is, in essence, built-in wastage – the user never has the ink in the first place.
Hewlett-Packard’s Research and development budget has been put to good use though. Instead of being built from two layers being bonded onto the silicon base, printheads used in the new systems are a single layer. Thus, there is no issue with poor alignment of the bonded layers that could result in poor performance and inaccurate firing of ink droplets, giving rise to poor dot positioning. In addition, the new printhead manufacturing technology allows smaller nozzles that are closer together – hence faster print speed in a single swath and smaller drop size.
As always, the new printer from Hewlett-Packard is an impressive piece of kit. As already indicated, the new PhotoSmart 8250 engine is the fastest printer of its kind, claiming 32ppm for draft black text (and experience shows that draft mode is more than adequate for the majority of mono applications).
In colour, the printer can achieve 31ppm for mixed text and graphics in draft mode. Raising the output to ‘laser printer quality’, quoted print speed is 10.7ppm which, Hewlett-Packard points out, is twice as fast as most four-pass colour laser printers.
As expected from a photo printer, memory card slots are provided, together with a PictBridge interface and the standard PC interface is high speed USB. An auto-duplex unit is available as an option.
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