Tilt compensating AGC

摘要

A correcting bias is applied to the video signal from a hand-held optical character reader to compensate for horizontal tilt of the hand-held reader and also to increase the acceptability of photodiode arrays which are used in the reader and to correct uneven sensitivity of the photoelements in the photodiode arrays. The analog video is changed to a four bit video and this four bit video is processed to produce a tilt error signal indicative of magnitude and direction of the tilt. This tilt error signal is then applied back as a compensating factor in the four bit analog to digital converter to compensate for the tilt of the hand-held reader.