The Visioneer OneTouch 9420 is a flatbed scanner much like the BenQ flatbed scanner 5000U listed on this website. The Visioneer One Touch 9420 Driver has been listed below for downloading and comes in Windows Vista / XP / 2000 versions. Note that this scanner is a bit odd in its drivers.
There are two drivers for the Visioneer OneTouch 9420. turn your scanner around and see the number under the scanner to download the correct driver as there are two versions of the exact same scanner. Note that this is the TWAIN and WIA Drivers.
Part Number 85-0240-x00
Part Number 85-0257-x00
Technical Support Tip: It is important to properly remove any previous driver versions before installing a new driver.