Symbol read device having separate gain controls for reading different scan lines

Abstract

A symbol read device which has separate gain controls for reading different scan lines. The symbol read device includes a light beam emitter, a scanner which scans the light beam over different positions on a symbol surface having a symbol to be read, a detector which detects light reflected from the symbol surface and generates a detection signal indicative thereof, and a variable gain amplifier which amplifies the detection signal. The device further includes a process which processes an amplified detection signal from the amplifier and recognizes therefrom the symbol being read, an automatic gain controller which sets a gain of the variable gain amplifier every scan line or scan line group in response to the detection signal, a scan position detector which detects a scan position, and a controller which selects the gain set by the automatic gain controller based on an output signal of the scan position detector.

Dependencies are inferred from the claim text.