Optics contamination prevention utilizing a coanda air deflection system

Abstract

In a document copier machine an almost completely enclosed optics module is provided to keep the optical components isolated from the remainder of the machine and thereby minimize contamination of the optical components. The described module has three large openings. One of these openings is an air inlet which opens to the exterior of the machine for bringing cooling air to a fan located inside the module. The second opening is an air outlet to allow the optics cooling air to exit. The third opening is critical to contamination and is an aperture which opens to the interior of the machine to allow illumination to pass from the optics module to a photoreceptive surface. In order to prevent air flow into the module through the aperture, louvers are situated at the fan to direct an airstream onto a first Coanda surface to move air toward the aperture. Light shields provided near the aperture to guard against stray light also provide an additional non-contamination function by capturing the airstream from the first Coanda surface and directing the airstream to the aperture. One of the shields can also act as a second Coanda surface in the transfer of air to the aperture. In that manner a positive flow of air out of the aperture is provided, thus preventing contamination of the optics module.