Irradiation device and image-reading device

摘要

An irradiation device increasing the lighting depth and facilitating the assembling is provided. A transparent bar-shaped light guide having LEDs disposed near ends thereof includes a first prism group and a first reflector, and, a second prism group and a reflector which are provided so as to extend in a lengthwise direction and which diffuse and reflect light. The light guide includes a first light outgoing area emitting reflected light as primary light Lm, and a second light outgoing area emitting reflected light as secondary light Ls. The first light outgoing area includes a plane portion forming a flat surface. A plane mirror reflects the secondary light Ls in a direction overlapping the primary light Lm in a read area.

主权项

1. An irradiation device comprising:
a light source that emits light; a transparent bar-shaped light guide having a circular cross section with radius R and the light source disposed near an end of the light guide; a first diffusion/reflection portion which is provided so as to extend in a lengthwise direction of the light guide, and which diffuses and reflects light propagating in an interior of the light guide; a first light outgoing area which is a portion of an outer surface of the light guide extending in the lengthwise direction and located in a reflection direction of the first diffusion/reflection portion, and which emits, as primary light, light reflected by the first diffusion/reflection portion; a second diffusion/reflection portion which is provided so as to extend in the lengthwise direction of the light guide, and which diffuses and reflects light propagating in the interior of the light guide; a second light outgoing area which is a portion of the outer surface of the light guide extending in the lengthwise direction and located in a reflection direction of the second diffusion/reflection portion, and which emits, as secondary light, light reflected by the second diffusion/reflection portion; a plane mirror that reflects the secondary light in a direction overlapping the primary light in a predetermined area; the second light outgoing area having a curvature of 1/R as viewed in the lengthwise direction of the light guide; the first light outgoing area that at least partially includes a curved portion having a curvature that is less than 1/R as viewed in the lengthwise direction; and the primary light having a wider divergence angle than that of the secondary light.