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Browse Prior Art Database

LASER SCAN "JAGGIES"

IP.com Disclosure Number: IPCOM000024654D
Original Publication Date: 1981-Jun-30
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 75K

Publishing Venue

Xerox Disclosure Journal

Abstract

Laser scanners as used with xerographic machines are capable of producing very well defined horizontal and vertical lines. However, slanted lines are subject to "jaggies" as in the example shown in Figure 1. This is because of the very high content of lines at small angles off perpendicular when the font being generated is slanted, which results in low frequency "jaggies" which can be very visible and objectionable. The source of the difficulty is attempting to produce such slants with a square character matrix.

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Page 1 of 2

XEROX DISCLOSURE JOURNAL

LASER SCAN "JAGGIES" Frederick R. Ruckdeschel Oscar G. Hauser

Proposed Classification
U.S. C1. 358/293

Int. C1. H04n 1/10

LINES

FIG. I

LINES

FIG. 2

Volume 6 Number 3 May/June 1981 151

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

Page 2 of 2

LASER SCAN VAGGIES" (Cont'd)

Laser scanners as used with xerographic machines are capable of producing very well defined horizontal and vertical lines. However, slanted lines are subject to "jaggies" as in the example shown in Figure 1. This is because of the very high content of lines at small angles off perpendicular when the font being generated is slanted, which results in low frequency "jaggies" which can be very visible and objectionable. The source of the difficulty is attempting to produce such slants with a square character matrix.

The problem can be greatly reduced by using a rectangular matrix instead of a square one such as shown in Figure 2. The matrix tilt can be generated by the addition of some simple electronics to a square array system, to delay the start of scan pulse, which synchronizes the scan lines by an amount depending on the scan line number.

The delay circuit could be for example, a counter/comparator combination. The counter, which is a resettable free-running counter, is reset upon receipt of the original end of scan pulse and counts up to a preset number. The comparator compares the signal output of the counter with a previously received start of scan signal and...