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Photoconductor Defect Analysis

IP.com Disclosure Number: IPCOM000062518D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Baldwin, TP: AUTHOR [+3]

Abstract

A scanning electron microscope (SEM) is used to concomitantly negatively charge and view a xerographic photoconductor, in order to find the site of minute, electrically conductive defects in the photoconductor. The photoconductor sample is mounted in the SEM, and electrical contact is established between the photoconductor's aluminized MYLAR* substrate (ground plane) and the ground of the SEM. The sample is then imaged in the SEM using secondary electron imaging. Since the photoconductor is an insulator in the absence of visible radiation, the SEM's electron beam causes the photoconductor's surface to develop a static negative charge. In the region of a defect (i.e., a conductive path to the ground plane), there are sufficient charge carriers to allow discharge of the SEM-generated electrons to ground.

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Photoconductor Defect Analysis

A scanning electron microscope (SEM) is used to concomitantly negatively charge and view a xerographic photoconductor, in order to find the site of minute, electrically conductive defects in the photoconductor. The photoconductor sample is mounted in the SEM, and electrical contact is established between the photoconductor's aluminized MYLAR* substrate (ground plane) and the ground of the SEM. The sample is then imaged in the SEM using secondary electron imaging. Since the photoconductor is an insulator in the absence of visible radiation, the SEM's electron beam causes the photoconductor's surface to develop a static negative charge. In the region of a defect (i.e., a conductive path to the ground plane), there are sufficient charge carriers to allow discharge of the SEM-generated electrons to ground. Thus, the defect region is viewed as dark relative to the other bright, electron-rich areas of the photoconductor. Once these dark areas are located, the sample is removed from the SEM, and these areas are subjected to an oxygen plasma etch, in order to slowly remove the various organic coatings (charge generation layer and charge transport layer, for example) comprising the photoconductor. The sample is periodically returned to the SEM, and, by again viewing the defect area, the exact location of the defect, through the thickness of the photoconductor, can be located, and the impurity or contamination can be identified through the us...