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Slotted Aperture

IP.com Disclosure Number: IPCOM000076697D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Williams, GT: AUTHOR

Abstract

An efficient illumination system is realized by use of a slotted aperture with parallel sides. This results in more efficient utilization of the light used for imaging the document on the photoconductor.

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Slotted Aperture

An efficient illumination system is realized by use of a slotted aperture with parallel sides. This results in more efficient utilization of the light used for imaging the document on the photoconductor.

The illumination system includes a tungsten lamp 1, an elliptical reflector 2 and an aperture 3 with parallel sides, Figs. 1 and 2. Reflector 2 is capable of focusing light on document 4, but the energy distribution along the footprint or parallel to the lamp tends to be less at the ends than at the center. The optics system, which images the document on photoconductor 5 mounted on drum 6, requires that in order for the irradiance to be constant transversely across the drum, the illumination must be higher at the ends than at the center. This loss is proportional to the inverse cosine fourth of the angle formed by the central ray and a ray to the point of concern.

Two end losses have been described which require some means be employed to either increase the amount of light at the ends or reduce the light in the center. Increasing the edge illumination is the more efficient approach. For this reason, end reflectors 7 and 8 are added to elliptical reflector 2 so that more light is reflected to the ends. These end reflectors are adjusted so that any light striking them is reflected to ends closest to the reflector. The light from the end reflectors is not focused and in order to achieve the necessary illumination level, the footprint must of necessi...