ISO/IEC 19752 - Cartridge Yield for monochrome laser printers.
The consumables in a printer have a limited life, proportionate
to how much ink or toner is used in a page and how many pages are
printed.
Cost per page is a very significant point in the value printers offer
to users. Printer manufacturers like to point to print quality, speed,
ease of use and costs of maintenance as potentially more important and
they have a point - for instance the cost of electricity and
replacement ETBs and fusers are significant part of the cost of owning
a printer. However users would rather like a plain statement on cost
per page and ISO/IEC 19752 is a significant move towards that.
Historically printer manufacturers agreed to measure the life of
consumables at 5% cover - roughly equivalent to a piece of
correspondence which was what printers were mainly used for in the
1990s.
Although 5% cover sounds a simple objective - generate a page with some
text. Printer manufacturers developed their own in house tests, most of
which probably were fair. However there was no guarantee of that, for
instance 5% cover could be a band of black covering 1/20th of the page
- that wouldn't necessarily be a fair test. Printer consumables
often last somewhat longer when the machine does one long print job of
several thousand pages because
there are fewer startup and cleaning revolutions, so that isn't a
realistic
test of use in the real world either.
It would also be open to manufacturers to take a printer from the
production line and fine tune it for the test - which wouldn't be at
all representative of what users might buy. With nothing said
about how the figures are arrived at a
manufacturer might even claim that the printer was designed to
give some level of economy without ever testing it at all.
ISO/IEC 19752 introduced in June 2004 sets out standards that remove
some of these wrinkles. For instance:
It requires toner consumption to be tested on three representative
printers using three cartridges each. The printers and cartridges are
not taken off the production line but bought in the open market from
three different sources. Sample size may seem small considering some
printers may sell in millions - but some sell in hundreds.
Standards are set for the test environment, temperature and humidity
change the electrostatic fields in a printer and affect yield.
The print mode should be the printer's default settings.
The ISO test target is a PDF called the "LSA page"; it has some text,
line art, shading and solid fill.
Paper is to be "conditioned" and of medium weight. If the printer goes
to an error condition then the ISO procedures set out a flow chart for
what is to be done. When a cartridge reaches exhaustion the standard
says how many times it can be shaken.
ISO also sets out definitions of terms and an example of the test
report and how to calculate the results.
There are a few problems with the ISO test
The three printers with three cartridges each procedure isn't a great
burden to manufacturers, who will expect to sell thousands of
printers. The expense is potentially a problem for cartridge
remanufacturers wanting to test their cartridges to the standard.
One problem with all ISO documents is that they aren't actually
available for free. ISO sells its documents online.
Another problem is that it only applies to monochrome, not to colour
printers. ISO has been developing tests for colour printers
and appears to be near finalisation at the time of witing (spring
2009). The standard will be 19798 Editors Paul Jeran and David
Spencer. "Method for the Determination of Toner Cartridge Yield for
Colour Electrophotographic Printer and Multi-Function Devices that
contain printer components."
