Archived from groups: comp.periphs.printers (
More info?)
I agree with most of your comments. Ultimately, we need a standard that
is agreed upon within the industry, and that should have happened long
ago, IMHO.
I was wondering, however, about one thing in your explanation, regarding
how the thermal technology works in terms of projecting the ink forward.
I understand that the ink is heated "behind" the most forward liquid
ink column to a point where the solvents are vaporized, to create an
expanding gas to propel the ink in front of it forward and out the
nozzle, but then what happens to that heated gas bubble? Does it have
enough time to get cooled so it goes back through change of state into
liquid form so there is no evaporation of the ink components? I could
see how that might work if the heating point is far enough behind the
ink column.
I find the description you provided on one manufacturer's 5% standard
amazing, well maybe outrageous would be a better term! The 5% (per
color) measurement is reasonable, I suppose, since many manufacturers
have used this as a standard, but I had no idea that anyone was
interpreting that 5% coverage to only be in a margined restricted area.
That seems quite "creative" shall we say, (I'd use the word
misleading). With those "standards" a manufacturer could decide the
area of 5% coverage could be as large or small as they wished. How
about a real 5% coverage over the full paper. Then, if some
manufacturer preferred to use a sample that was 10% coverage over 50% of
the area it would still be the same thing (or nearly so) if they felt
that more accurately represented the usage their clients would have.
Allowing manufacturers to decide the area of the paper that would
contain the 5% coverage of a letter sized page is not any sort of
standard, and makes the whole comparative process a bit of a joke.
And, as others have mentioned, some type of long range study should be
done to include and average initial purge, cleaning cycles, cartridge
change cycles, individual ink cartridges versus ganged cartridges,
quality of text or image, and so on, so we, as consumers, can get some
realistic numbers to evaluate.
This is similar to the problem that occurred with flatbed scanners and
"resolution" where some manufacturers would use outrageous interpolated
number to advertise the resolution of the scanner. HP was one of the
companies that handled this one properly and conservatively, using
interpolated numbers no higher than twice optical, and I commended then
for their honest use of the numbers. Some companies literally suggested
interpolated resolution values of 10 x the optical, which anyone who
understands interpolation, recognizes completely degrades the image,
since that type of interpolation brings in massive errors.
Art
Bob Headrick wrote:
> "Arthur Entlich" <artistic@telus.net> wrote in message
> news:Crs3e.147610$gJ3.144633@clgrps13...
>
>>These generalizations are just that. Just about every Epson and HP printer
>>model use different ink cartridges holding differing amounts of ink. The
>>Epson inks should, in theory, go further per liquid measure, because they do
>>not need to be boiled or heated to be printed with.
>
>
> This is a bit misleading - the ink is not boiled away in the HP design. A tiny
> layer of ink is vaporized, pushing the ink droplet out the nozzles. The vapor
> bubble very quickly collapses back into liquid inside the printhead.
>
> The pages per ml will be more strongly impacted by the dye (or pigment) loads,
> the dot gains of the particular ink and media, the print modes (how the ink is
> applied, how it is layered to make millions of colors, etc). Servicing also
> has a large impact on real pages out. Different systems have different method
> and requirements for the amount and frequency of servicing required.
>
> From the customer standpoint the important factors are not drops per ml but
> pages per $ (or insert local currency here) and perhaps pages per cartridge
> which takes into account the inconvenience of having to replace cartridges..
> Currently this is a bit difficult to compare without some homework, as
> different manufacturers use different test methods, samples and definitions.
> One manufacturer specifies a 5% page, but the fine print notes that the
> 8.5"x11" page has 1" borders on all four sides - the are printed at 5% is only
> a 6.5" x 9" page. There is currently an ISO standard being developed that will
> allow more direct comparisons of page yields, with controlled standards and
> reporting methods. This effort is currently expected to be ratified by the end
> of 2005.
>
> Regards,
> Bob Headrick, not speaking or my employer HP
>
>
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