Browse Prior Art Database

TONER IMAGE INPUT SCANNER WITH SEQUENTIAL SCREENING

IP.com Disclosure Number: IPCOM000025148D
Original Publication Date: 1983-Oct-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 69K

Publishing Venue

Xerox Disclosure Journal

Abstract

In multi-function COPY, READ, WRITE systems employing the xerographic pro-cess, documents are read and the image content thereof converted to electrical signals or pixels in the READ mode. This is effected by raster scanning the document image after the document image has been developed on the photo-receptor and prior to transfer or erasure thereof, such scanning being effected by sweeping a laser beam across the developed image and capturing and converting the reflected light pattern to electrical signals. However, it appears that essentially no gray scale information can be achieved with this system in the case of continuous tone originals due to the blindness of the scanning laser to the height of the discrete toner piles that comprise the developed image. On the other hand, it has been found that gray scale is reasonably preserved when halftone documents are processed.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 67% of the total text.

Page 1 of 2

XEROX DISCLOSURE JOURNAL

TONER IMAGE INPUT SCANNER WITH SEQUENTIAL SCREENING Charles J. Kramer

Proposed Classification
U.S. C1. 358/283 Int. C1. H04n 1/36

In multi-function COPY, READ, WRITE systems employing the xerographic pro- cess, documents are read and the image content thereof converted to electrical signals or pixels in the READ mode. This is effected by raster scanning the document image after the document image has been developed on the photo- receptor and prior to transfer or erasure thereof, such scanning being effected by sweeping a laser beam across the developed image and capturing and converting the reflected light pattern to electrical signals. However, it appears that essentially no gray scale information can be achieved with this system in the case of continuous tone originals due to the blindness of the scanning laser to the height of the discrete toner piles that comprise the developed image. On the other hand, it has been found that gray scale is reasonably preserved when halftone documents are processed.

To permit continuous tone document images to be read in multi-function systems of this type, it is proposed, in the case of continuous tone document, that the latent electrostatic image be sequentially screened prior to development. The sequential screen pattern may be generated with a fixed screen but could also be generated through control of the laser modulator. Such screenine converts the continuous tone information into a pulse wide di...