Document reader lamp life extension system

摘要

An optical character reader for conversion of information to a machine readable code from a strip of alpha-numeric characters on the face of a document. It includes an elongated document slot along which the document may be hand guided through a predetermined path. Optical viewing means is provided across a scan line intersecting the path of the alpha-numeric characters. A character scanning assembly electronically generates images of each character. Recognition processing means encodes these images into a machine readable code. All of the physical, optical and electronic components are contained within a compact single enclosure. Incandescent lamps are utilized to illuminate the document face across the scan line. The usable life of each lamp is extended by providing a constant current source in the operational lamp circuit. Incandescent lamps are utilized to illuminate the face of the document across the scan line. Lamp life is extended by dimming of the lamps when they are nonoperational, maintaining the lamps in a state of excitation beyond the crystalline state of the material comprising the lamp filaments. A second form of lamp life extension is provided by interposing a constant current source in the electrical power supply connected to the lamps in their operational state.