Digital BW, The Print

At 09:07 +0100 3.3.2003, Ernst Dinkla wrote:
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>
>And Canon hasn't variable droplet sizes yet ?  Seems unlikely.
>

It is quite easy imagine how to produce two size of drop mechanically 
- add two different electric potentials on the same piezocrystal and 
you receive for example - 4 and 9 pl. Add more different drops and 
you receive three possible sizes of drop in one step: 4, 9 and 22 
(9+9+4) pl. And 13 (4+9), 26 (4+9+4+9), 36 (4+9+4+9+4+9) pl for 360 
dpi.

But how to make the same with thermal head? With two different 
thermal elements for one nozzle? Is it mechanically possible?

Anytime you are limited with cooling of print head. So you may not 
increase the frequency of firing of drops ad lib.  (IRIS has solved 
it very effectively - there is a continual production of drops which 
cool the head - with only ONE nozzle per color.)

Very high number of nozzles has one positive effect though - it 
covers the irregularities of firing of drops better. Drops fired by 
piezo are about 100 times faster and the precision is much higher, 
but one may see any irregularity.

Martin


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