Comment 20 for bug 217571

The VPablos fix doesn't work for me on Ubuntu Jaunty 9.04, because it disables both of my USB mice multiseat setup. What I had to do for my Fujitsu 4120c is to add file
/etc/udev/rules.d/45-libsane.rules
with the following content

# Fujitsu fi-4120C
SYSFS{idVendor}=="04c5", SYSFS{idProduct}=="1041", MODE="664", GROUP="scanner"

I also had to add group scanner

sudo addgroup scanner

and add myself and other users which should have access to the scanner to this group

sudo adduser some_username scanner

After reboot scanning works beautifully. This rule came from
http://forum.ubuntu-fr.org/viewtopic.php?pid=2707917
but the venfor and product can by discovered simply by running

xxx@yyy:~$ sane-find-scanner
...
found USB scanner (vendor=0x04c5, product=0x1041) at libusb:002:002
...