LASER SCANNING CODE SYMBOL READING SYSTEM

摘要

A laser scanning symbol reading system includes an analog scan data signal processor for producing digital data signals, wherein during each scanning cycle, a light collection and photo-detection module generates an analog scan data signal corresponding to a laser scanned symbol, a multi-channel parallel scan data signal processor/digitizer processes the analog scan data signal along multiple cascaded multi-stage signal processing channels, to generate digital data signals corresponding thereto, while a synchronized digital gain control module automatically processes the digital data signals in response to start of scan (SOS) signals generated by a SOS detector. Each signal processing channel supports different stages of amplification and filtering using a different set of band-pass filtering and gain parameters in each channel, to produce multiple digital first derivative data signals, and/or multiple digital scan data intensity data signals, having different signal amplitudes and dynamic range characteristics for use in decode processing.

主权项

1. A symbol reading system, comprising:
a scanning module for scanning a light beam across a scanning field in a scanning cycle, the scanning module comprising an oscillating mechanism for scanning the light beam across the scanning field; a scan line detector for detecting a start of each scanning cycle performed by the scanning module and generating a start of scan (SOS) signal in response to the detection of the start of each scanning cycle; a photo-detector for detecting the intensity of light reflected from the scanning field and generating a first signal corresponding to the detected light intensity; a signal processor, comprising:
a first processing channel for generating a first data signal and a first derivative data signal, the first processing channel having:
a first differentiation stage for processing the first signal and generating a first derivative signal; anda first amplification stage for amplifying the first signal and the first derivative signal using a gain; anda second processing channel for generating a second data signal and a second derivative data signal and having a second amplification stage for amplifying the amplified first signal and the amplified first derivative signal generated by the first amplification stage using a fixed gain; a gain control module for, during each scanning cycle, controlling the gain of the first processing channel's first amplification stage within the signal processor using the SOS signal generated by the scan line detector, the first data signal and the first derivative data signal generated by the first processing channel, and the second data signal and the second derivative data signal generated by the second processing channel; a decode processor for processing the first data signal, the first derivative data signal, the second data signal, and the second derivative data signal and generating data representative of a symbol in the scanning field; and a hand-supportable housing having the scanning module, the scan line detector, the photo-detector, the signal processor, the gain control module, and the decode processor disposed therein.