Light guide member, illuminating device, and image reading apparatus and image forming apparatus using same

Abstract

The present invention provides a light guide member, an illuminating device, and an image reading apparatus and an image forming apparatus using the same. The light guide member includes a main body part, and an entrance surface, a strip-shaped exit surface and a strip-shaped reflecting surface that are formed on the main body part. The illumination light is output from the exit surface. The reflecting surface extends in the first direction on a face placed opposite to the exit surface of the main body part and reflects the illumination light. The reflecting surface includes, on a flat face, a reflection pattern surface provided with a plurality of minute reflective concave parts having a function of reflecting the illumination light toward the exit surface. The reflective concave parts each include a deflection surface which deflects the illumination light in a direction in which a reflection angle widens in a cross sectional view in a second direction that is orthogonal to the first direction in a horizontal direction, and then reflects the illumination light. Accordingly, it is possible to output a uniform illumination light using a light guide member of a minimal size.

Description

Background technique [0001] The present invention relates to a light guide body for guiding illumination light emitted from a light source, a lighting device using the light guide body, and an image reading device and an image forming device using the lighting device. [0002] In an image forming apparatus such as a scanner or a copier, an illumination device that irradiates light on a document sheet is used in order to optically read an image of a document sheet. In recent years, a white LED (Light Emitting Diode: Light Emitting Diode) having an advantage of high luminous efficiency has been used as a light source of the lighting device. In such an illuminating device, the document sheet needs to be illuminated linearly, but since LEDs are point light sources, a rod-shaped light guide and the white LEDs are combined to generate linear illuminating light. The light guide body has: an incident surface arranged at one end of the light guide body for entering the illumination li...

AI Technical Summary

Problems solved by technology

This leads to an increase in the overall length of the light guide, hindering the miniaturization of the lighting device

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