Provided is an image sensor lighting unit including at least one light guide extending in a main scanning direction; a first light source group facing a first end surface of at least two end surfaces of the at least one light guide in the main scanning direction; and a second light source group facing a second end surface of the at least two end surfaces. The first light source group includes a first light source that emits light having a predetermined wavelength band. The second light source group includes a second light source that emits light having the wavelength band. An X-coordinate of the first light source in a corresponding XY-coordinate system is equal in absolute value to an X-coordinate of the second light source in a corresponding XY-coordinate system, with the at least one light guide viewed from the first end surface side in the main scanning direction.

A display device includes a non-translucent cover, a light source provided inside the cover, and a translucent light display that is transmissive to light from the light source. The light display has a protrusion disposed in a through opening of the cover. The protrusion fitted into the through opening from the inside spans a first side surface and a second side surface of the cover, and protrudes outward from the outer surface of the cover to form a light guide. The light guide has a smaller thickness in a corner portion corresponding to a connection region between the first side surface and the second side surface than in other portions thereof.

An image sensor unit includes: a visible light cut filter that is arranged between a first light source and a first light guide and blocks light including visible light having wavelengths longer than those of ultraviolet light; a lens body that condenses light generated on a reading target by light radiated from the first light guide and light radiated from a second light guide; a line sensor that receives the light condensed by the lens body; and an ultraviolet light cut filter arranged between the lens body and the line sensor and blocks ultraviolet light.

An illumination device includes a light guide member having a first side in a main scanning direction and a second side in a sub-scanning direction and a plurality of light sources including first light emitters respectively to emit beams of light of a first color and a second light emitter to emit a beam of light of a second color different from the first color toward an inside of the light guide member via a side of the light guide member in the main scanning direction. The first light emitters are positioned in the sub-scanning direction to be symmetrical to each other.

An image reading apparatus includes a light emitter to irradiate a document with light, a first light guide to guide the light reflected by the document, an output device to output a readout signal obtained from the light reflected and guided by the first light guide, a base to correct shading in the readout signal, and circuitry to output a scanned image in which the shading of the document in the readout signal is corrected, based on correction data obtained from the readout signal of the base output from the output device, control a timing at which the light emitter emits the light and a timing at which the output device outputs a signal, and heat the first light guide with the light emitted from the light emitter before the output device outputs the readout signal of each of the document and the base.

An illumination device includes light sources and a light guide member. The light guide member includes an incidence part that guides light emitted from the light sources and entering through an incidence surface towards a center of the light guide member and a central part that has a scattering surface for emitting the guided light towards an illumination target body. The light sources include a first light source facing the incidence surface and a second light source facing the incidence surface and is arranged on the central part's side relative to the first light source. The incidence part has a first curved surface that reflects the light entering through the incidence surface towards the central part and a second curved surface that is arranged on the central part's side relative to the first curved surface and reflects the light entering through the incidence surface towards the central part.

A light guide includes a first exit portion emitting first exiting light, a second exit portion emitting second exiting light in a different direction than the first exiting light, and a reflecting portion reflecting light entering the light guide to each of the first and second exit portions. The first and second exit portions respectively have first and second curved surfaces each having a convex cross section perpendicular to the long axis direction. The second exit portion is connected to the first exit portion in the direction perpendicular to the long axis direction. The reflecting portion is provided, in a plane facing the first exit portion and the second exit portion, at a position shifted in the direction perpendicular to the long axis direction from a position where a normal to the plane passes through a connection portion between the first and second exit portions.

An image reading apparatus includes a light-guide member that moves in a direction crossing a longitudinal direction of the light-guide member and that emits light, which has entered from an incident surface of the light-guide member, as light that is linearly distributed in the longitudinal direction, a light source that emits the light, and an optical fiber that guides the light emitted by the light source to the incident surface.

An imager is provided. The imager has an imaging platen which presents an imaging surface against which an object to be imaged can be placed. The imaging platen has a photodetector layer and a light guiding layer operable to guide light towards the object. The imager includes a light source operable to emit light into the light guiding layer. The light source is located at an edge of the light guiding layer, to guide light into the light guiding layer of the imaging platen.

A reading apparatus includes an irradiation unit that performs irradiation with light, a light receiving unit that receives light reflected from an object to be imaged, a first optical path in which specularly reflected light, which is obtained as light emitted by the irradiation unit is reflected from a first reflection surface so that a front surface of the object to be imaged in an irradiation region is irradiated with the reflected light, and the reflected light is specularly reflected from the front surface of the object to be imaged, is guided to the light receiving unit as a read image, a second optical path in which diffusely reflected light, which is obtained as the light emitted by the irradiation unit is reflected from a second reflection surface so that the front surface of the object to be imaged in the irradiation region is irradiated with the reflected light, and the reflected light is diffusely reflected from the front surface of the object to be imaged, is guided to the light receiving unit as a read image, and a switching section that switches between the first optical path and the second optical path by rotating the irradiation unit.