Browse Prior Art Database

Copier Illumination Device

IP.com Disclosure Number: IPCOM000088785D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Maddox, RA: AUTHOR [+2]

Abstract

This illumination device includes a lamp situated in the neighborhood of the center of curvature of a rear spherical reflective mirror together with a mating front spherical mirror of similar radius of curvature. This front mirror has a shaped aperture in order to spatially control the lamp's light intensity profile. The rear mirror and shaped front mirror form an optical cavity, and, due to the redistribution of the light within the cavity, result in increased illumination efficiency within the desired viewing angle.

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Copier Illumination Device

This illumination device includes a lamp situated in the neighborhood of the center of curvature of a rear spherical reflective mirror together with a mating front spherical mirror of similar radius of curvature. This front mirror has a shaped aperture in order to spatially control the lamp's light intensity profile. The rear mirror and shaped front mirror form an optical cavity, and, due to the redistribution of the light within the cavity, result in increased illumination efficiency within the desired viewing angle.

Fig. 1 shows a portion of a copier having a stationary document glass or platen 10, a stationary lamp and reflector assembly 11, a stationary paraboloid mirror 12, and a movable mirror 13. An opaque, black mask 14, mounted in front of mirror 12, controls distribution of the light which is reflected from mirror 12 to mirror 13. This light then is reflected off mirror 13 onto platen 10. As a result, light is reflected from the document's light/dark areas onto the copier's photosensitive material (not shown).

Reflector 15 is a spherical reflector encasing substantially the back half of tungsten-halogen lamp 16, and directing light toward mirror 12 and mask 14. A second mating, partially hemispherical reflector 17 forms an optical cavity with reflector 15. The top surface contour of reflector 17 is substantially identical to the top surface contour 18 of mask 14, as this mask is "mapped" back onto a sphere with lamp 16 at its...