Illumination device and image reading device

• Main Authors: Matsuzawa, Taku, Ohama, Daisuke, Shiraki, Toru, Kunishio, Hideki
• Format: Patent
• Language: English
• Published: 02.06.2020
• Subjects: ACCESSORIES THEREFOR; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USINGWAVES OTHER THAN OPTICAL WAVES; APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FORPROJECTING OR VIEWING THEM; CINEMATOGRAPHY; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; ELECTROGRAPHY; HOLOGRAPHY; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHOTOGRAPHY; PHYSICS; PICTORIAL COMMUNICATION, e.g. TELEVISION

An illumination device includes a light source and a rod-like light guide extending in a longitudinal direction for guiding incident light to an object to be illuminated. The light source is disposed at an end of the light guide extending in a longitudinal direction. The light guide includes an incident surface at the longitudinal end to receive light emitted from the light source, a flat emission surface to emit light incident on the light guide toward the object to be illuminated, a parabolic reflective surface to reflect, toward the emission surface, light from a focus of the paraboloid shape of the refractive surface or light passing through the focus from a predetermined area, and a light-scattering portion, having a predetermined area, to scatter light entering through the incident surface and reflect the light toward the reflective surface. The light-scattering portion is placed at the focus of the paraboloid shape or at a position where light reflected by the scattering area on the light-scattering portion passes through the focus.