Illumination device and image reading device

An illumination device comprising:

• a rod-shaped light guide extending in a longitudinal direction and configured to guide light entering from an end surface and emit the light as linear light from a lateral surface;
• a light guide holding portion having
• a hole into which the end surface of the light guide is inserted,
• a light guide insertion portion having an opening provided on an opposite surface opposite to a surface in which the end surface of the light guide is inserted, the opening optically communicating with the hole, and
• a light source base plate that is arranged on the opposite surface-side and that includes a light source to emit light through the hole;
• a supporter supporting the light guide holding portion slidably along the longitudinal direction;
• and
• a housing supporting or housing the light guide, the light guide holding portion, and the supporter, at least the supporter being fixed to the housing, wherein
• a direction of sliding of the light guide holding portion is restricted to the longitudinal direction by a supporter-side concave-convex portion that is a supporter-side groove portion or a supporter-side protruding portion, at least one of the supporter-side groove portion or the supporter-side protruding portion being formed on the supporter along the longitudinal direction,
• the supporter includes two of the supporter-side concave-convex portions facing each other, and the light guide holding portion is arranged between the two supporter-side concave-convex portions,
• the supporter supports the light guide holding portion with the light guide holding portion exposed in an imaginary plane on which the longitudinal direction intersects with a facing direction in which the two supporter-side concave-convex portions face each other,
• the housing includes a concave portion that is recessed along a height direction perpendicular to the imaginary plane and that supports or houses at least the light guide holding portion and the supporter, and
• the illumination device further comprises an engaging portion that is formed along the height direction, projects from the supporter on a side of the supporter opposite to a side on which the light guide holding portion is arranged, and touches the concave portion.

An illumination device comprising:

• a rod-shaped light guide extending in a longitudinal direction and configured to guide light entering from an end surface and emit the light as linear light from a lateral surface;
• a light guide holding portion having
• a hole into which the end surface of the light guide is inserted,
• a light guide insertion portion having an opening provided on an opposite surface opposite to a surface in which the end surface of the light guide is inserted, the opening optically communicating with the hole, and
• a light source base plate that is arranged on the opposite surface-side and that includes a light source to emit light through the hole;
• a supporter supporting the light guide holding portion slidably along the longitudinal direction;
• and
• a housing supporting or housing the light guide, the light guide holding portion, and the supporter, at least the supporter being fixed to the housing, wherein
• a direction of sliding of the light guide holding portion is restricted to the longitudinal direction by a supporter-side concave-convex portion that is a supporter-side groove portion or a supporter-side protruding portion, at least one of the supporter-side groove portion or the supporter-side protruding portion being formed on the supporter along the longitudinal direction,
• the light guide holding portion includes a light guide holding portion-side concave-convex portion that has a shape corresponding to a shape of the supporter-side concave-convex portion and that is formed along the longitudinal direction, and
• the light guide holding portion-side concave-convex portion is formed in the light guide insertion portion.