Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

PIXEL AVERAGING FOR IMAGE BAR UNIFORMITY CORRECTION

IP.com Disclosure Number: IPCOM000026273D
Original Publication Date: 1991-Feb-28
Included in the Prior Art Database: 2004-Apr-05
Document File: 4 page(s) / 149K

Publishing Venue

Xerox Disclosure Journal

Abstract

Image Bar Raster Output Scanners (ROS), such as PLZT and LED arrays, are much more compact and often cheaper than polygon ROS devices. A major problem with using image bars, however, is that the images they produce are less uniform in irradiance than images produced by a single light source ROS such as a laser polygon scanner. The non-uniformity occurs because an image bar is made up of several thousand light sources, or attenuators, one per pixel, each varying somewhat in radiance. Instead of using one source element per image pixel for the entire line time, several different source elements can be used during the line time for that one image pixel. This averaging of source elements would tend to make the image more uniform. The non-uniformity will decrease as the number of elements averaged increases. To accomplish the averaging without losing resolution, the desired pattern is first formed across the image bar and imaged onto the photoreceptor. Then, during the line time, the pattern is electronically shifted laterally across the bar. The optical system would compensate for this and image the shifted pattern registered on the first image at the photoreceptor. Additional smoothing out of the non-uniformity will be achieved by repeating the procedure of shifting the pattern on the image bar and imaging it in registration many times during the line time. The number of source elements that can be averaged will be limited by the electronic data rate and complexity of the optical shift device. Averaging over many elements will increase the electronic clocking rate but only one raster line of data is used during the line time. Shifting the pattern laterally in one element increments is not necessarily the optimum. The amount of shift used in a given type of image bar could be set to filter or average out the largest component in its non-uniformity frequency spectrum or a frequency to which the eye is very sensitive.

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 54% of the total text.

Page 1 of 4

XEROX DISCLOSURE JOURNAL

PIXEL AVERAGING FOR IMAGE BAR UNIFORMITY CORRECTION U.S. C1.346/160 Robert P. Loce

Proposed Classification

Int. C1. Gold 15/14

IMAGE BAR

i

lllloolol IA

L~+,-l-,-l-l-l- 11 0 0 10 llB

I I I I I I I

FIG. 1

XEROX DISCLOSURE JOURNAL - Vol. 16, No. 1 January/February 1991 17

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

Page 2 of 4

PIXEL AVERAGING FOR IMAGE BAR UNIFORMITY CORRECTION (Cont'd)

Image Bar Raster Output Scanners (ROS), such as PLZT and LED arrays, are much more compact and often cheaper than polygon ROS devices. A major problem with using image bars, however, is that the images they produce are less uniform in irradiance than images produced by a single light source ROS such as a laser polygon scanner. The non-uniformity occurs because an image bar is made up of several thousand light sources, or attenuators, one per pixel, each varying somewhat in radiance. Instead of using one source element per image pixel for the entire line time, several different source elements can be used during the line time for that one image pixel. This averaging of source elements would tend to make the image more uniform. The non-uniformity will decrease as the number of elements averaged increases. To accomplish the averaging without losing resolution, the desired pattern is first formed across the image bar and imaged onto the photoreceptor. Then, during the line time, the pattern is electronically shifted laterally across the bar. The optical system would compensate for this and image the shifted pattern registered on the first image at the photoreceptor. Additional smoothing out of the non- uniformity will be achieved by repeating the procedure of shifting the pattern on the image bar and imaging it in registration many times during the line time. The number of source elements that can be averaged will be limited by the electronic data rate and complexity of the optical shift device. Averaging over many elements will increase the electronic clocking rate but only one raster line of data is used during the line time. Shifting the pattern laterally in one element increments is not necessarily the optimum. The amount of shift used in a given type of image bar could be set to filter or average out the largest component in its non-uniformity frequency spectrum or a frequency to which the eye is very sensitive.

One embodiment of an image bar...