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Electrophotographic Arrangement

IP.com Disclosure Number: IPCOM000076591D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Castro, G: AUTHOR [+2]

Abstract

The illumination of pure homogeneous organic photoconductors in their long-wavelength absorption region mainly produces nonconducting excitons. Charge carriers are produced by illumination with shorter wavelength or higher energy light, The process at short wavelengths is not very efficient by itself and much of the incident energy is converted into heat. The efficiency of the short-wavelength generation can be enhanced if there is a simultaneous illumination with long-wavelength light, which produces excitons near the illuminated surface. The excitons by virtue of their diffusion properties have a high probability for finding charge carriers. The interaction of the excitons with the charge carriers, enhances the probability of separation of electron-hole pairs by a process not yet fully understood.

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Electrophotographic Arrangement

The illumination of pure homogeneous organic photoconductors in their long- wavelength absorption region mainly produces nonconducting excitons. Charge carriers are produced by illumination with shorter wavelength or higher energy light, The process at short wavelengths is not very efficient by itself and much of the incident energy is converted into heat. The efficiency of the short-wavelength generation can be enhanced if there is a simultaneous illumination with long- wavelength light, which produces excitons near the illuminated surface. The excitons by virtue of their diffusion properties have a high probability for finding charge carriers. The interaction of the excitons with the charge carriers, enhances the probability of separation of electron-hole pairs by a process not yet fully understood. For example, the excitons may increase the kinetic energy of the electron to overcome germinate recombination, or the excitons may change the current-carrying capability of the material.

In the arrangement shown in the drawing, the exciton enhancement can be used to increase the photosensitivity of the photoconductor as an electrophotographic element. The virtue of this arrangement, as opposed to illuminating the document with both lights, is that the long-wavelength source can be directly focused on the photoconductor at high intensity without causing any photoconductivity itself, but only enhancing that produced by the shorter wavel...