Browse Prior Art Database

Dual Mirror Document Scanning System

IP.com Disclosure Number: IPCOM000075774D
Original Publication Date: 1971-Nov-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 6 page(s) / 189K

Publishing Venue

IBM

Related People

Bruce, GD: AUTHOR [+7]

Abstract

In this system, a second image projection means is added to the scanning system described in U.S. Patent 3,497,298 to obtain greater copying output, without increasing the electrophotographic process speeds, and eliminate the return time required to get the translating mirror into the position at which a scanning operation is begun. A document illumination function is added to the scanning mechanism.

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Dual Mirror Document Scanning System

In this system, a second image projection means is added to the scanning system described in U.S. Patent 3,497,298 to obtain greater copying output, without increasing the electrophotographic process speeds, and eliminate the return time required to get the translating mirror into the position at which a scanning operation is begun. A document illumination function is added to the scanning mechanism.

Fig. 1 shows the essential parts required to scan a document placed atop flat glass plate 1 through lens 2, the optical axis of which is perpendicular to the document, so that images are placed on continuously rotating drum 3. Each scanning operation occurs as a mirror, which is perpendicular to the document, is translated from position 5 to position 4. The direction of scanning depends on the copying process used and on the direction of rotation of drum 3. It is assumed that the image is used to discharge a previously charged photoconductor on the surface of drum 3 for a subsequent development and transfer to paper, and that the direction of rotation of the drum is as shown by arrow 6. Otherwise, the scanning mirror might be required to travel from position 4 to position 5 during each scanning operation. The document width scanned is determined by aperture plate 7. Lower mirror 8 is positioned, as shown, to direct the image from lens 2 to drum 3. The scanned document area may be illuminated by a pair of lamps 9 used with associated reflectors 10 focusing light on the document after reflection off scanning mirror 4, and reduction mode copying of larger originals may be accomplished by translating lens 2 to position 11, by moving mirror 8 into position 12, and by increasing the velocity of the scanning mirror so that it reaches position 13 at the end of each scanning operation.

A second scanning mirror is brought into start position 5 as the original scanning mirror reaches the and of its travel at position 4. The second mirror is used for the next scanning operation with the original mirror removed from the optical path. Alternate use of the two scanning mirrors allows greater copying output, without increasing the electrophotographic process speeds associated with drum 3, by eliminating the return time required to get the scanning mirror from position 4 to position 5.

Fig. 2 shows a pair of scanning mirrors 14 and 15 driven by chain assemblies 16 and 17, respectively, and held by carriage assemblies 18 and 19, respectively, so that the mirror surfaces are always perpendicular to the document surface, not shown. Chain drive sprockets 20 and 21 are driven in the direction of arrows 22, 23 in synchronism with the photoconductor drum, not shown. Mirror 14 moves downwardly in the middle of a scanning operation, while mirror 15 is returned upwardly behind it.

Mirror 15 is attached by cantilever support structure 24 to bearing assembly 25, which slides horizontally on rails 26. These rails are mounted on...