FUJITSU fi-4220C2 - Manual (Page 136)

GL-10
Ultrasonic sensor
A type of sensor for detecting multi feeding by ultrasonic sound. Scanners detect multi
feeding by recognizing differences in the amount of ultrasonic waves that penetrates the
documents.
USB (Universal Serial Bus)
An abbreviation for "Universal Serial Bus". A standard for interfaces used to connect
devices such as key boards, scanners, etc. Up to 127 devices can be connected through
this interface. USB devices can be plugged/unplugged without turning off their power.
Data transfer rates are different between the "Low speed mode" (1.5Mbps) and "High
speed mode" (Max. 12Mbps).
White level follower
A function to correct the difference between white colors in unbleached paper (e.g. wood
containing paper, etc.) and in scanned images.
White Reference Stripe
The white part located in the ADF that defines the lightest area in an image, causing all
other areas to be adjusted accordingly.