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START-OF-SCAN AND END-OF-SCAN OPTICAL ELEMENT FOR A RASTER OUTPUT SCANNER

IP.com Disclosure Number: IPCOM000026561D
Original Publication Date: 1992-Oct-31
Included in the Prior Art Database: 2004-Apr-06
Document File: 4 page(s) / 239K

Publishing Venue

Xerox Disclosure Journal

Abstract

Figure 1 shows a scanning system for use with an electrophotographic printer in which disclosed start-of-scan and end-of-scan optical element 30 is disposed. Laser source 10 produces collimated laser beam 12 which is reflected from the facets of rotating polygon 14. Each facet of polygon 14 in turn deflects laser beam 12 to create an illuminated beam spot 16 on the pre-charged surface of photoreceptor 18. The system may further include additional optical elements such as focusing lenses 15. The periodic scanning of beam spot 16 across the moving photoreceptor 18 creates an array of scan lines 20. Optical element 30 elongated in the scan direction is adapted for the transmission of light therethrough in a direction transverse to the scan direction. Optical patterns 32 and 34 along a portion of optical element 30 in the scan direction include at least one surface for the non-transmission of light passing transverse to the scan direction. Areas 32 and 34 having optical patterns therein are most usefully placed at the areas along the scan direction corresponding to the end points of scan line 20.

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Page 1 of 4

XEROX DISCLOSURE JOURNAL

START-OF-SCAN AND END-OF- Proposed Classification SCAN OPTICAL ELEMENT FOR A
RASTER OUTPUT SCANNER
Frank C. Genovese

U.S. C1.346/160 Int. C1. Gold 15/00

FIG. 2A

FIG. 2B n

XEROX DISCLOSURE JOURNAL - Vo1.17 No. 5 September/October 1992 317

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Page 2 of 4

START-OF-SCAN AND END-OF-SCAN OPTICAL ELEMENT FOR A RASTER OUTPUT SCANNER (Cont'd)

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318 XEROX DISCLOSURE JOURNAL - Vo1.17 No. 5 September/October 1992

[This page contains 1 picture or other non-text object]

Page 3 of 4

START-OF-SCAN AND END-OF-SCAN OPTICAL ELEMENT FOR A RASTER OUTPUT SCANNER (Cont'd)

Figure 1 shows a scanning system for use with an electrophotographic printer in which disclosed start-of-scan and end-of-scan optical element 30 is disposed. Laser source 10 produces collimated laser beam 12 which is reflected from the facets of rotating polygon 14. Each facet of polygon 14 in turn deflects laser beam 12 to create an illuminated beam spot 16 on the pre-charged surface of photoreceptor 18. The system may further include additional optical elements such as focusing lenses 15. The periodic scanning of beam spot 16 across the moving photoreceptor 18 creates an array of scan lines 20. Optical element 30 elongated in the scan direction is adapted for the transmission of light therethrough in a direction transverse to the scan direction. Optical patterns 32 and 34 along a portion of optical element 30 in the scan direction include at least one surface for the non-transmission of light passing transverse to the scan direction. Areas 32 and 34 having optical patterns therein are most usefully placed at the areas along the scan direction corresponding to the end points of scan line 20.

Optical patterns 32 and 34 are used to provide real-time feedback to the scanning system for registration of successive scan lines 20 to form raster 22 on photoreceptor 18. Because all scan lines must pass through optical element 30 as the scan line is made, optical pattern 32 may be used to ensure that the first bit of digital data for a particular scan line will be output when beam spot 16 is positioned on photoreceptor 18 for the first pixel in scan line 20. This registration is made possible by the real-time feedback created by optical pattern 32, which is physically placed at the start of each scan line.

Figure 3A shows one arrangement of optical element 30 with support substrate 36, with detailed views in Figures 3B, 3C and 3D. Optical element 30 may also include additional optical member 38, which may be in the form of a cylindrical lens and prism 40 here formed as part of member 38. Detector 42 is mounted in a position to detect the optical modulation of light against the optical pattern area, and is disposed relative to prism 40 and optical pattern area 32 in such a way that, when beam spot 16 is generally near one endpoin...