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Lighting Configuration for Video Scanning System

IP.com Disclosure Number: IPCOM000074070D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Boone, JW: AUTHOR

Abstract

For lighting the document platen of a video scanning system, a series of standard fluorescent lamps 11 are arranged in truncated cone fashion, at an angle of 13 degrees with reference to the axis of the cone. Four fill-in lamps 13 are positioned in square-array, just underneath and outwardly bounding aperture 15 of platen surface 17. A diffusing surface 19, of truncated configuration, extends between top 21 and bottom 23 of a lamp supporting structure. Bottom 23 is also a diffusing surface. This lighting structure yields a light gradient from center to edge of the scanned document, which has a Cos/4/ fall off for a given objective lens. The document scanned may be illuminated uniformly in the plane of the light sensitive surface of the scanning system.

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Lighting Configuration for Video Scanning System

For lighting the document platen of a video scanning system, a series of standard fluorescent lamps 11 are arranged in truncated cone fashion, at an angle of 13 degrees with reference to the axis of the cone. Four fill-in lamps 13 are positioned in square-array, just underneath and outwardly bounding aperture 15 of platen surface 17. A diffusing surface 19, of truncated configuration, extends between top 21 and bottom 23 of a lamp supporting structure. Bottom 23 is also a diffusing surface. This lighting structure yields a light gradient from center to edge of the scanned document, which has a Cos/4/ fall off for a given objective lens. The document scanned may be illuminated uniformly in the plane of the light sensitive surface of the scanning system. With tubular fluorescent lamps 11 disposed in truncated cone fashion at a predetermined angle with respect to platen surface 17 and diverging in a direction away from the platen surface, an elimination of direct reflection of lamps 11 into the used field angle of the objective lens is effectively achieved. Diffusing surfaces 19 and 23 yield a very uniform platen surface 17, somewhat similar to that obtainable from an integrated light sphere. The purpose of using the four fluorescent tubes 13 as fill- in lamps, is to gradually increase the incident light on the platen, from center to edge, for obtaining Cos/4/ distribution.

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