Browse Prior Art Database

FIXED FULL WIDTH ARRAY SCAN HEAD CALIBRATION APPARATUS

IP.com Disclosure Number: IPCOM000026158D
Original Publication Date: 1990-Aug-31
Included in the Prior Art Database: 2004-Apr-05
Document File: 6 page(s) / 253K

Publishing Venue

Xerox Disclosure Journal

Abstract

A primary problem associated with electronic input scanners is a periodic requirement for calibration of the sensor arrangement. Because a large number of photosensitive elements make up the scanning array, uniformity of response is necessary for good imaging quality. However, varying electronic characteristics of the sensors, aging illumination sources, and varying mechanical tolerances within a scanning device all contribute to variations in the light intensity response of the sensors in the device. Frequent calibration is required against a target having a known reflectance value.

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XEROX DISCLOSURE JOURNAL

FIXED FULL WIDTH ARRAY SCAN HEAD CALIBRATION APPARATUS Wayne A. Buchar
Keith A. Nau
Pierre A. Lavallee

Proposed Classification
U.S. C1.355/235 Int. C1. GOlj 1/40

XEROX DISCLOSURE JOURNAL - Vol. 15, No. 4 July/August 1990 249

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FIXED FULL WIDTH ARRAY SCAN HEAD CALIBRATION AP P ARATUS(Cont'd)

F/G. IB

250 XEROX DISCLOSURE JOURNAL - Vol. 15, No. 4 July/August 1990

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

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FIXED FULL WIDTH ARRAY SCAN HEAD CALIBRATION APPARATUS(Cont'd)

FIG. IC

XEROX DISCLOSURE JOURNAL - Vol. 15, No. 4 July/August 1990 251

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

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FIXED FULL WIDTH ARRAY SCAN HEAD CALIBRATION APPARATUS( C ont 'd)

A primary problem associated with electronic input scanners is a periodic requirement for calibration of the sensor arrangement. Because a large number of photosensitive elements make up the scanning array, uniformity of response is necessary for good imaging quality. However, varying electronic characteristics of the sensors, aging illumination sources, and varying mechanical tolerances within a scanning device all contribute to variations in the light intensity response of the sensors in the device. Frequent calibration is required against a target having a known reflectance value.

In Figures 1A-lC, for calibration and service purposes, fixed upper scanning element 32 may be journaled for rotation out of its scanning position with respect to the paper path, in order to bring the optical and sensor arrangement to a position to view an on-board test pattern. Scanning element 32 is supported for rotation about an axis R, where axis R is arranged generally transverse to the direction of paper path movement through the scanning station and parallel to the imaging plane P. Scanning element 32 is supported via a pair of brackets (not shown) at both inboard (operator side of the scanning device) and outboard (the opposite side of the device from the operator) ends thereof on a pair of shaft or pivot members 200 (outboard side only shown), which in turn are supported for free rotating movement on the machine frame within a bearing member 202. On the outboard side of the device, pivot member 200 also supports in fixed engagement therewith a scanning element pulley member 204, rotation of which causes pivot member 200, and thus, scanning element 32 to rotate about axis R. Pulley member 204 is driven through its rotational movement with a drive or timing belt 206 wrapped therearound, with the opposite end of timing belt 206 opposite end wrapped around motor pulley member 207 supported on a drive shaft 208 connected to stepper motor 210. Pulley members 204 and 207, and timing belt 206 may have complementary teeth for positive driving engagement between the belt and pulley members.

Stepper motor 210 is controllably driven with a motor controller 220, responsive to wha...