11 Nov
2012
11 Nov
'12
1:57 p.m.
Laser printer toner tends to be mono component, that
is it does not
require a separate carrier or developer to transport it to the
photoreceptor and is magnetic. Copier toner tends to require a separate
carrier that is made of a coated magnetic powder. The Carrier is
recycled and not consumed, but does wear out over time.
Small desktop copiers, like the Canon one that started this discussion
seem to have monocomponent toner too. At least, there is one reservoir
inside the cartridge ,the toner seems to be one material, and it is
magnetc. Jaut like laser printer toner.
Laser printers work by charging a light sensitive, semiconducting drum
or belt, the charge will vary depending on the type of material used.
The drum may be charged positive or negative. A laser or LED array will
then erase certain parts of the charge on the photoreceptor, then
depending on which and how much charge the toner carries it will stick
to either the charged or discharged areas. These charges are always
different even on m/c's made by the same company so toners are rarely
the same between m/c's.
How does this differ , in principle, from the operaiton of a small
photocopier? The sort of copier we're discussign works by having a
photosensitive drum. It is first given a precodnitioning exposure
(essentially to discharge it, btu that is an oversimplification), then it
is charged, thne light reflected fro mteh origianl is focussed on the
drum. Then chargerd toner is applied. Then the toner is pulled from the
drum onto the paper by the 'tranfer corona wire' under the paper.
Jsut like a lasrt printer, in fact.
Also fusing tempratures of these toners are different. not enough heat
and you can rub the toner from the sheet, too much it sticks to the
fusing rollers..
Is ther eay reason in principle why a photocopier has to use a differnt
fussing temperature to a laser printer. If so, what is this reason?
-tony