Welch Allyn, Inc.

Jeffrey B Powers

William H Havens

Gerard Frederick Beckhusen

William H Lagerway

Charles M Hammond

Mark A McClaude

Kenneth A Wright

Harry R McKinley

Joseph J Morabito

Theresa M West

An apparatus for illuminating an indicia in a sensing region of an object plane. A housing has a median longitudinal vertical plane and a horizontal scanning plane. A reflector for reflecting light directed thereagainst toward the sensing region has a first approximately curvilinear profile in a plane parallel to the scanning plane, and a second approximately curvilinear profile in a plane parallel to the median longitudinal plane. The central portion of the reflector defines an opening whereby light from the sensing may return in generally the same plane as light directed toward the sensing region.

Illumination apparatus for optical readers

There is disclosed an apparatus for illuminating a sensing region having an object therein, comprising a reflector that is elongated in a first plane, the reflector having a width dimension that is less than a width dimension of a sensing region to be illuminated, and further having a first curved profile in the first plane about a center of curvature. In a preferred embodiment the reflector is disposed between the center of curvature and the sensing region. In a second plane which is orthogonal to the first plane and includes the center of curvature, a reflecting surface of the reflector has a second curved profile. A plurality of substantially Lambertian light sources each face the reflector for directing light thereto generally in a direction of the center of curvature for reflection toward the sensing region. The second profile preferably comprises a portion of an ellipse and a light source is disposed substantially at a primary focus thereof. The second profile preferably has a gap for transmitting retroreflected light generated within the sensing region therethrough. An upper portion of the second profile comprises a portion of a first surface of revolution selected from the group of ellipse and parabola, and the lower portion of the second profile can comprise a portion of a second surface of revolution selected from the group of ellipse and parabola, a light source being disposed at a focus of each of the first surface of revolution and the second surface of revolution. The assembly is combined in a scanner for reading optical patterns.

Illumination system for optical reader

There is disclosed an simplified apparatus that enables optical scanners to achieve minimum field curvature and at the same time provide uniformly distributed light on an image sensor. A single element lens, preferably an aspherical lens made of a plastic material is combined with an aperture stop. The combination is capable of reducing lens aberrations and minimizing image field curvature for an object plane that contains indicia to be scanned or read. A suitably demagnified image of the indicia is focused onto an image sensor such as a CCD array. The spatial light distribution function in the image plane can be equalized by an attenuator, such as a neutral density filter or a slit, suitably configured to compensate for the reduced optical efficiency at large field angles. An aspherical lens containing a dye or a cold mirror can be used for limiting light transmission to a range of wavelengths.

Optical assembly and apparatus employing same using an aspherical lens

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Skaneateles, NY, United States of America

Jeffrey B Powers