Posted by Nils Miller, Ph.D., HP Ink and Media Senior Scientist
 
In my last post I described the press event in general and explained why we wanted the journalists to experience the challenges of designing a printer. In this post, I'll describe how this DaPS ‘Virtual Printer’ works and the insights the journalists (and HP) obtained.

Let’s start with the left-hand column in the blue-bordered table below – the engineering inputs -- starting at the top with ‘Inkset Type’. The journalists had 5 inkset types from which to choose. They had about half an hour to inspect various print samples on plain paper and photo paper, as well as perform their own tests directly on some samples to determine the water resistance and scratch resistance performance of each inkset. I also showed them faded sample prints so they could visualize what each inkset would look like after approximately 5 years of display in a customer’s home.

Inkset B was the most popular choice by a large margin because the journalists felt that Inkset B combined good photo vibrancy, durability and fade resistance, while still being vivid and sharp on plain paper. It was fascinating for me to listen in on each team’s internal discussions (arguments, in many cases) about the relative importance of each attribute, and how much to trade off one attribute in order to improve another. HP has found that most of our home-printing customers expect good-looking, long-lasting photographs from their HP printer, but also want their plain paper prints to look vibrant and sharp. The journalists tended to agree with this approach.

The journalists were given just two choices of photo paper to optimize the printer around: a less-expensive and thinner photo paper, and a higher-quality, better-looking, more expensive photo paper. The vote was roughly 50%/50% on this choice, as we expected.

The number of inks in the printer is another very important design decision. Sometimes when you read magazines you get the impression that journalists think ‘more is better’, but these experienced reviewers of computers and printers, tended to practicality, and chose 4 or 6 ink configurations. They understood that more ink colors make the printer bigger and more expensive, and this exercise was focused on designing a relatively inexpensive (less than $150) ‘do it all’ printer. HP’s desktop printers have for many years been primarily 4 and 6 ink configurations, for many of the same reasons the journalists identified.

The next decision concerned Drop Volume. Smaller is better, right? Well, the journalists quickly learned that the answer is ‘not necessarily’. Small can be good for photo image quality, but it slows down plain paper print speeds. After carefully inspecting real-life print samples for ‘grain’, most of the journalists chose drop volumes in the 3 or 4 pl range as an optimal size.

‘Nozzles per inch’ – this sounded a bit technical, but they soon learned that packing lots of nozzles per inch has many benefits for speed and quality, without significantly adding cost to the printer. Because of the ‘dpi (dots per inch) wars’ of years past, we expected that many would choose the highest nozzle per inch number, but surprisingly most journalists thought that 600 nozzles per inch was high enough.

‘Swath Height’ is another techy engineering term, but it simply indictes how many nozzles the print head has. Surprisingly, most resisted the urge to choose the biggest, and went for the moderate (1/2 inch) size. Good thing too – had they chosen the 1 inch size, the size and cost of the printer would have increased dramatically.

‘Ink Delivery System’ touched on another sometimes controversial area. For many years, HP has researched customer printing behavior at home and concluded that for many, an ‘integrated print head’ (IPH) design was a good choice.  IPH means the printhead and ink supply cartridge are all on one easy-to-replace unit, with no extra tubes. HP has had ‘Separate Ink and Silicon’ (SIS) designs for well over a decade, but has tended to use them only for applications that use a lot more ink per month.  SIS is also known as individual ink tanks meaning each ink color can be replaced separately. Apparently journalists have become more educated on this topic over the years, because many of them chose an IPH design for this printer.  However, SIS was still the more popular choice made by more than half of the teams.

‘Ink Supply Page Yield’ relates to the size of the ink supplies. As we expected, some of the journalists wanted to know the ‘milliliters’, but we explained that since some inks are more efficient than others, what really matters is the number of pages the ink supply can produce. The journalists resisted the urge to choose a really big supply, since this increases the size and cost of the printer. 

After an hour of learning the background necessary to make reasonable input decisions, each team of journalists chose a final set of inputs and handed them to us. While they took a break, we calculated the predicted performance of their printer on the 11 customer attributes you see listed on the right hand side of the chart above. Most of these attributes are self-explanatory, except ‘Ink Supply Replacement Rate’ (which indictes how often the customer will have to replace one of the ink supplies). In each of the 5 sessions, we let the journalists vote on what customer attributes are the most important, and based on that vote we were able to give extra weighting to those attributes. While each session voted differently, in general most agreed that cost – either of the printer, or on a cost-per-photo basis – was very important.

It was a very fun and interesting week. The journalists did a great job in learning the key principles behind the engineering and ink chemistry decisions that HP makes. Their comments indicated they learned the importance of looking at the overall ability of a printer to meet the needs of all customers—rather than focusing on one or two exciting specs that sound good but detract from other important attributes.

Opinions expressed here and in any corresponding comments are the personal opinions of the original authors, not of HP and may not have been reviewed in advance by HP.