Patent ID: 6527186
Filing Date: 2003-03-04
Classification: G02B,G06K,G07F,G07G,H01M,Y02E

Abstract:
A scan data signal processor for use with a host laser scanning system capable of producing a laser beam having a plurality of focal zones within a predefined depth of field, scanning the laser beam across a bar code symbol within said predefined depth of field and producing an analog scan data signal in response thereto, said scan data signal processor comprising:a preamplification circuit for preamplifying an analog scan data signal produced in response to scanning a bar code symbol with one of said plurality of focal zones; a first derivative signal generating circuit for deriving a first derivative signal from said preamplified analog scan data signal; a variable pass-band filter having pass-band filter characteristics for processing a signal selected from the group consisting of said preamplified analog scan data signal and said first derivative signal; a control signal generation circuit for generating a control signal indicative of the focal distance of the scanned laser beam producing said analog scan data signal provided to said preamplification circuit; and a filter control circuit for dynamically controlling the pass-band filter characteristics of said variable pass-band filter using said control signal, thereby automatically tuning said scan data signal processor to an optimum setting for the focal zone being scanned at each given moment of operation of said host laser scanning system.