Browse Prior Art Database

OSCILLATING SELFOC LENS ARRAY FOR HIGH QUALITY LED PRINTBARS

IP.com Disclosure Number: IPCOM000026892D
Original Publication Date: 1994-Apr-30
Included in the Prior Art Database: 2004-Apr-07
Document File: 2 page(s) / 67K

Publishing Venue

Xerox Disclosure Journal

Abstract

High quality, high resolution LED printbars are a combination of an array of LED sources and a Selfoc lens array. The Selfoc lens array images the LED sources onto the photoreceptor of a xerographic machine whereby uniform, high resolution halftones are a copy/print quality requirement for the mid volume family of digital products. To achieve the required uniformity, the exposure levels of each pixel are corrected, on a pixel-by-pixel basis, by either changing the pixel current or its associated "ON" time. In the process, exposure nonuniformity created by the Selfoc lens array are also corrected and thus there is no apparent need to oscillate the lens array during an exposure interval to correct exposure non-uniformity at the image plane.

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XEROX DISCLOSURE JOURNAL

OSCILLATING SELFOC LENS Proposed Classification ARRAY FOR HIGH QUALITY LED
PRINTBARS
Int. C1. G03b 27/00 James D. Rees

U.S. C1.25511

High quality, high resolution LED printbars are a combination of an array of LED sources and a Selfoc lens array. The Selfoc lens array images the LED
sources onto the photoreceptor of a xerographic machine whereby uniform, high resolution halftones are a copy/print quality requirement for the mid volume family of digital products. To achieve the required uniformity, the exposure levels of each pixel are corrected, on a pixel-by-pixel basis, by either changing the pixel current or its associated "ON" time. In the process, exposure nonuniformity created by the Selfoc lens array are also corrected and thus there is no apparent need to oscillate the lens array during an exposure interval to correct exposure non-uniformity at the image plane.

However, this pixel-by-pixel correction does not compensate for variations in the Selfoc lens array Modulation Transfer Function (MTF) along its length. If these MTF variations are locally abrupt, streaks result in the high frequency xerographic line screens or halftones. It is therefore proposed that the LED printbar Selfoc lens array be oscillated to smooth out abrupt Selfloc lens MFT variations created by a tilted Selfoc fiber or the like. The oscillation frequency should be high and with a corresponding low amplitude.

REFERENCES:

U.S. Patent No. 4,982,222 to Rees disclo...