Apparatus and method for automatic gain control during scanning

Abstract

The disclosure describes an apparatus and method for automatic gain control during scanning. The apparatus comprises an optical detector to receive an optical signal reflected from a symbol positioned within a scan window by an optical beam scanned from a leading edge of the scan window to a trailing edge of the scan window; and a processor coupled to the optical detector to adjust the gain of the optical detector during the beam scan. The process comprises receiving an optical signal using an optical detector, wherein the optical signal comprises optical energy reflected from a symbol positioned in a scan window as an optical beam scans from a leading edge of the scan window to a trailing edge of the scan window, and adjusting the gain of the optical detector during receipt of the optical signal. A calibration process is disclosed comprising calibrating the optical detector to obtain a plurality of gain corrections, each gain correction corresponding to a different position between a leading edge and a trailing edge of a scan window, and storing the plurality of gain

Description

TECHNICAL FIELD The present invention relates generally to scanners, and in particular, but not exclusively, to automatic gain adjustment during scanning. BACKGROUND Bar code scanners typically function by generating a thin beam of light and scanning the beam across a symbol to be read. The symbol typically comprises a plurality of alternating light (usually white) and dark (usually black) areas; the best-known symbols are bar codes, where the light and dark areas are formed by a white background with alternating black bars superimposed thereon. As the spot created by the projection of the beam onto the symbol travels across the symbol, it crosses the alternating light and dark areas and a portion of the light hitting the symbol is reflected back into the scanner. More light is reflected from the light areas than from the dark areas, so the optical energy reflected back into the scanner will consist of a signal containing a series of peaks corresponding to the light areas and vall...

Examples

Embodiment Construction

Embodiments of an apparatus and method for automatic gain control during scanning are described herein. In the following description, numerous specific details are described to provide an understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in this specification do not necessarily all refer to the same embodiment. Furthermore, the part...

TECHNICAL FIELD The present invention relates generally to scanners, and in particular, but not exclusively, to automatic gain adjustment during scanning. BACKGROUND Bar code scanners typically function by generating a thin beam of light and scanning the beam across a symbol to be read. The symbol typically comprises a plurality of alternating light (usually white) and dark (usually black) areas; the best-known symbols are bar codes, where the light and dark areas are formed by a white background with alternating black bars superimposed thereon. As the spot created by the projection of the beam onto the symbol travels across the symbol, it crosses the alternating light and dark areas and a portion of the light hitting the symbol is reflected back into the scanner. More light is reflected from the light areas than from the dark areas, so the optical energy reflected back into the scanner will consist of a signal containing a series of peaks corresponding to the light areas and vall...

Examples

Embodiment Construction

Embodiments of an apparatus and method for automatic gain control during scanning are described herein. In the following description, numerous specific details are described to provide an understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in this specification do not necessarily all refer to the same embodiment. Furthermore, the part...

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