Browse Prior Art Database

COMPOUND OPTICS FOR A RASTER OUTPUT SCANNER IN AN ELECTROPHOTOGRAPHIC PRINTER

IP.com Disclosure Number: IPCOM000026663D
Original Publication Date: 1993-Feb-28
Included in the Prior Art Database: 2004-Apr-06
Document File: 8 page(s) / 410K

Publishing Venue

Xerox Disclosure Journal

Abstract

The present disclosure relates to an optical arrangement for a compact, low-error raster out ut scanner (ROS) system suitable for multicolor printing. In

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XEROX DISCLOSURE JOURNAL

Proposed Classification
U.S. C1.359/204

COMPOUND OPTICS FOR A RASTER OUTPUT SCANNER IN AN ELECTROPHOTOGRAPHIC Int. C1. G02b 26/08 PRINTER
Frank C. Genovese

12d

12

30

XEROX DISCLOSURE JOURNAL - Vol. 18, No. 1 Januaryrnebruary 1993 87

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NG. I

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COMPOUND OPTICS FOR A RASTER OUTPUT SCANNER IN AN ELECTROPHOTOGRAPHIC PRINTER(Cont'd)

18 Y

36 7

FIG. 2

FIG. 3

88 XEROX DISCLOSURE JOURNAL - Vol. 18, No. 1 January/February 1993

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COMPOUND OPTICS FOR A RASTER OUTPUT SCANNER IN AN ELECTROPHOTOGRAPHIC PRINTER(Cont'd)

FIG. 4

XEROX DISCLOSURE JOURNAL - Vol. 18, No. 1 JanuaryIFebruary 1993 89

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COMPOUND OPTICS FOR A RASTER OUTPUT SCANNER IN AN ELECTROPHOTOGRAPHIC PRINTER(Cont'd)

The present disclosure relates to an optical arrangement for a compact, low- error raster out ut scanner (ROS) system suitable for multicolor printing. In

raster output scanner (ROS) as a source of signals to be imaged on a pre- charged photoreceptor (a photosensitive plate, belt, or drum) for purposes of xerographic printing. The ROS provides a laser beam which switches on and off, or modulates, according to digital image data associated with the desired image to be printed as the beam moves, or scans, across the photoreceptor. A common technique for effecting this scanning of the beam across the photoreceptor is to employ a rotating polygon surface; the laser beam from the ROS is reflected by the facets of the polygon, creating a scanning motion of the beam, which forms a scan line across the photoreceptor. Once a latent image is formed on the photoreceptor, the latent image is subsequently developed with toner, and the developed image is transferred to a copy sheet, as in the well- known process of xerography.

In a rotating-polygon scanning system, there is a practical limit to the rate at which digital information may be processed to create an electrostatic latent image on a photoreceptor. One practical constraint is the maximum polygon rotation speed. It can be appreciated that high quality images require precision placement of the raster scan lines as well as exact timing to define the location of each picture element or pixel along each scan. In purely optical terms, there is a trade-off between speed and resolution in a scanning system. The higher the resolution, that is, the more pixels that are designed to form a latent image of a given size, the lower the numerical aperture of the optical system required in order to define the pixels accurately.

Referring to the figures, Figure 1 shows an arrangement of optical elements for full-color electrostatic printing from a source of digital data, according to the present invention, while Figure 2 illustrates the function of a cylindrical lens 36 in a raster output scanner. The curvature and position o...