stevens@hsi.com (Richard Stevens) (10/26/89)
I've run a PostScript "ruler" program on both our Apple LW+s
and find the x-axis is stretched a little and the y-axis is
compressed a little. But on a real PostScript typesetter
(a Linotronic L300) the measurements are perfect.
What causes the LW+ to do this ? Is there some form of
adjustment that can be made ? Are other brands of PostScript
laser printers "better" at this than the LW+ ?
Richard Stevens
Health Systems International, New Haven, CT
stevens@hsi.com
... { uunet | yale } ! hsi ! stevenshenry@utzoo.UUCP (11/16/89)
>... the x-axis is stretched a little and the y-axis is >compressed a little. But on a real PostScript typesetter >(a Linotronic L300) the measurements are perfect. The problem here is that the manufacturer of the printer couldn't be bothered to get it spot-on. The y-axis resolution is determined by the relationship between paper motion and laser scan rate, and usually is fixed by the print engine. The old Canon engine (which is what's in the LW+, LaserJet, etc etc.) was close to 300/inch but not dead on. I haven't checked the new Canon engines. The x-axis resolution is set by the "video" rate from the printer controller board. This is normally set by a crystal oscillator on the board. Many manufacturers prefer to use a standard oscillator that's almost right rather than paying for a custom part that exactly matches the y-axis resolution. If you're willing to spend some money and void your warranty, you can change oscillators to make the x-axis match the y-axis. Nothing you can do without a lot of machine-shop work will change the y-axis. Typesetter manufacturers generally have a fussier audience -- the printing types who reject output for flaws visible only under a magnifier -- and more money to spend on getting things just right. Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu