APPARATUS FOR AND METHOD OF ELECTRO-OPTICALLY READING A TARGET IN THE PRESENCE OF AMBIENT LIGHT BY REJECTING THE AMBIENT LIGHT

摘要

A reader for electro-optically reading a target in the presence of ambient light to be rejected, includes a laser for emitting a laser beam, a scan component for scanning the laser beam over a scan angle across the target, a photodetector for generating an output signal by detecting return laser light from the target to generate an information signal bearing information related to the target, and by concomitantly detecting the ambient light to generate an ambient light signal, and signal processing circuitry for measuring the ambient light signal to determine a threshold, for processing the output signal by passing the output signal through a filter having a bandwidth, and for rejecting the ambient light signal from the output signal by adjusting the scan angle and/or the bandwidth when the ambient light signal exceeds the threshold.

主权项

1. A reader for electro-optically reading a target in the presence of ambient light to be rejected, comprising:
a laser for emitting a laser beam; a scan component for scanning the laser beam over an adjustable scan angle across the target for reflection and scattering therefrom as return laser light; a photodetector for generating an output signal by detecting the return laser light from the target to convert the detected return laser light into an analog electrical information signal bearing information related to the target, and by concomitantly detecting the ambient light to convert the detected ambient light into an analog electrical ambient light signal; signal processing circuitry for processing the output signal, the signal processing circuitry including a controller for measuring the ambient light signal to determine a threshold, and a filter having an adjustable bandwidth, the signal processing circuitry being operative for rejecting the ambient light signal from the output signal by adjusting at least one of the scan angle and the bandwidth when the ambient light signal exceeds the threshold; and wherein the signal processing circuitry further includes a digitizer that receives the output signal through the filter with adjustable bandwidth, the digitizer being configured to determine points in the output signal that represent bar edges of a symbol on the target.