Digital BW, The Print

Ernst,

I'm not so sure you'd benefit from using the more inkjets for BO
printing but it's hard to know for sure.  If you had a printer that had 
inconsistent jets using more different jets might help in banding
problems though.   If you could intelligently (i.e. custom special
driver) do the microweave algorithms you might be able to get a
speed improvement.

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Ernst Dinkla" 
<E.Dinkla@c...> wrote:
> 
> ----- Original Message ----- 
> From: "Editor P.O.V. Image Service" <editor@p...>
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Sent: Monday, December 29, 2003 4:45 PM
> Subject: Re: [Digital BW] Multihead BO (theoretical more or less)
> 
> 
> > 4 colour printer should be adequate. The new R800 (7  heads,
> >not yet available) has the finest droplet size so far but which
> >existing 4 colour printer comes next ?
> >
> 
> >The C84 has 3 picoliter minimum drop size.. with six sizes of
> variable
> drops.. It's designed for  the DuraBrite inks.. It's Black head
> has 180
> nozzles, the color head has 177 nozzles (59 per color)<
> 
> The six sizes are most likely not all used in one setting. At
> 2880 you get most likely a range of 3 with the minimum droplet
> included. You need all the CMY heads to add a substantial nozzle
> quantity in this case. Wonder whether the droplet size variation
> is equal for the CMY and the K head. Any idea ?

All the variable droplet sizes I've seen so far have up to 3 sizes at
a particular resolution -- (two bits are sent to the printer for each
position 0=no dot, 1=small dot, 2=medium dot, 3=large dot).
I've never seen it mentioned in the docs that the dotsizes of CMY
versus K could be different -- gimp-print assumes they are the same.

At a resolution of 2880x1440 I think the printers all use just the
smallest dot.  At 1440x720 they typically use all 3 sizes.  The
dotsize ratios vary but 4pl, 8pl, 16pl (picoliters) is in the ballpark.
Consider a rectangle 1/1440 x 1/720 inch,  at 1440x720 you
could have 4, 8, or 16pl of ink, at 2880x1440 you can have up
to 4 drops of 4pl ink or 4, 8, 12, 16pl.

I'm not sure, but it may be theoretically possible to overprint an
additional dot over an existing dot on subsequent passes.  You 
certainly could if you were using all the jets with BO.

> 
> 
> >If you go to 6 colors, the 960 has 2 picoliter drops.. BUT, it's
> designed for dye-based inks.. The Black head has 192 nozzles...
> The
> color head has 480 nozzles (96 per color).  I don't know haow
> many sizes
> of drops the 960 has..<
> 
> Has it been used with third party pigment ? The 2 picolitre is
> nice and the range of droplet sizes doesn't matter that much as
> long as the number of heads used is high enough to divide the
> range so the printer is forced to use the minimal droplet. 672
> nozzles means 3,7 x the number of black head nozzles of the Epson
> 10000 that can print acceptable BO with 8 passes. Minimum droplet
> size of the last is 5 picolitre. Using the 960 with 4 passes
> still brings 4,5x better quality potential.
> 
> Meanwhile I wonder whether the deflection of the minimal droplets
> is so high compared to bigger droplets that there is no advantage
> because the detail is lost from say 50 to 100%. That can only be
> checked with trials.

My feeling is that there really isn't detail down to the 1440 or 2880
dpi range, you need those dpi's to take advantage of dithering for
smoothness.

> 
> Ernst

Roy