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Illumination Source for Line Scanner

IP.com Disclosure Number: IPCOM000048312D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Grimm, MA: AUTHOR [+2]

Abstract

In Fig. 1, a line of light 10 is projected onto document glass 12 by apertured fluorescent lamp 14 and elliptic-cylindrical light guide 16. Fig. 2 shows the apparatus in cross section.

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Illumination Source for Line Scanner

In Fig. 1, a line of light 10 is projected onto document glass 12 by apertured fluorescent lamp 14 and elliptic-cylindrical light guide 16. Fig. 2 shows the apparatus in cross section.

The fluorescent tube is apertured to concentrate its output light in a 30- degree arc on its surface. The elliptic-cylindrical lens 16 is formed from acrylic or styrene and has a highly polished surface so that light entering the lens from the fluorescent tube will be internally reflected until it exits near the document glass. Light entering the tube at focal point F1 of the ellipse is internally reflected and directed to focal point F2 of the ellipse. Focal point F2 lies on the line of light 10 at the upper surface of the document glass 12.

The exit radius R (Fig. 2) of the elliptic-cylindrical lens should be in the range given by the following expression: 2B Less Than R Less Than Square Root of A/2/-B/2/

In this expression, B is the minor semi-axis of the ellipse and A is the major semi-axis of the ellipse. The eccentricity of the ellipse is greater than 0.9 preferably.

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