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Document Scanning Mechanism

IP.com Disclosure Number: IPCOM000078576D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 44K

IBM

Related People

Davidge, RV: AUTHOR

Abstract

A minimal inertia mechanism optically scans a flat document surface so that the scanned image is focused about a line, as required to image a rotating copying machine drum.

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Document Scanning Mechanism

A minimal inertia mechanism optically scans a flat document surface so that the scanned image is focused about a line, as required to image a rotating copying machine drum.

Fig. 1 shows the scanning system. Document 1 placed on flat glass platen 2 is scanned across distance A through stationary lens 4, the axis of which is perpendicular to document 1, by mirrors 5 and 6, which translate through distances B. The image thus produced is focused about a line 8, perpendicular to the drawing on the surface of drum 9 rotating in direction 10. Throughout the scanning operation, mirrors 5 and 6 are held at a 45-degree angle 11 with respect to the lens axis 12 and a line 13 perpendicular to the image area, respectively. This way, the image axis line 14 is held parallel to the scanning axis line 15 as required for focusing the image. With drum 9 rotating in direction 10, mirrors 5 and 6 move in directions 16 and 17, respectively, scanning document 1 in direction 18. To image full size, distance C, which is twice the focal length of lens 4, is equal to the sum of distances D, E, and F; and the extensions of the surfaces of mirrors 5 and 6 move in the scanning operation through distances G, which are equal to half the scanning distance A. Therefore, the mirrors themselves move through distances B, equal to distances G multiplied by the sine of 45 degrees. (That is, distance B equals 0.354 times distance A.)

Fig. 2 shows a typical mechanism by which...