Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!apple!bionet!agate!labrea!glacier!jbn
From: jbn@glacier.STANFORD.EDU (John B. Nagle)
Newsgroups: comp.sys.next
Subject: Re: How did they make the printer so expensive? ->resolution
Message-ID: <17798@glacier.STANFORD.EDU>
Date: 24 Oct 88 02:43:12 GMT
References: <5807@zodiac.UUCP> <17784@glacier.STANFORD.EDU> <16961@shemp.CS.UCLA.EDU> <7099@ut-emx.UUCP> <7590@bloom-beacon.MIT.EDU> <7221@ut-emx.UUCP>
Reply-To: jbn@glacier.UUCP (John B. Nagle)
Organization: Stanford University
Lines: 22


     Worth pointing out is that simply sending more dots per inch to the
engine will not necessarily increase the resolution.  At some point, the
resolution of the xerographic process itself becomes the limiting factor.
It would be simple enough to crank a laser printing engine up to 600 DPI,
for example, just by cutting the spot size down, doubling the speed of
the rotating mirror, (or doubling the number of facets), and 
quadrupling the data rate to the laser.  But with today's engines, it
wouldn't really provide 600 DPI resolution; the xerographic process doesn't
have the resolution.  Xerographic copiers, for example, still can't copy a
magazine page without a major loss of detail.  There are limits to what can
be accomplished with a selenium photoconductor as the imaging medium, and,
in this, the fiftieth aniversary year of xerography, we seem to be very
near those limits.

     This may be a good reason to finally move away from xerography and toward
other processes, such as ion-implantation printing, for which the physical
limits inherent in the process are higher.  I doubt that we will ever have
the equivalent of glossy magazine pages coming out the slot of a xerography
based printer.

					John Nagle