An image sensor module includes a light source unit that emits a linear light beam elongate in a primary scanning direction to an object to be read, and a lens unit including an incidence surface and an output surface oriented opposite to each other. The lens unit is configured to receive light from the object through the incidence surface and output the light through the output surface. The module also includes a sensor IC that receives the light outputted from the output surface, a housing that holds the light source unit and the lens unit, and a support member that supports the lens unit such that the incidence surface is located more distant from the sensor IC than the output surface in a secondary scanning direction. The support member includes a reflection surface that reflects the light from the object toward the incidence surface.

An image sensor module includes a light source unit that emits a linear light beam elongate in a primary scanning direction to an object to be read, and a lens unit including an incidence surface and an output surface oriented opposite to each other. The lens unit is configured to receive light from the object through the incidence surface and output the light through the output surface. The module also includes a sensor IC that receives the light outputted from the output surface, a housing that holds the light source unit and the lens unit, and a support member that supports the lens unit such that the incidence surface is located more distant from the sensor IC than the output surface in a secondary scanning direction. The support member includes a reflection surface that reflects the light from the object toward the incidence surface.

An image reading device includes (i) light guides extending in a main scanning direction and configured to emit light from a light source toward a reading target moving relatively in a sub-scanning direction, the light from the light source being projected into end surfaces of the light guides in the main scanning direction, (ii) an optical filter arranged between the light source and the end surfaces of the light guides and configured to block or attenuate light having a specific wavelength from the light from the light source, (iii) a lens body to focus reflected light reflected by the reading target onto a light receiver to convert the reflected light into an electrical signal, and (iv) a lens holder. The lens holder includes a first positioner for positioning the light guides and a second positioner for positioning the optical filter.

An image reading device includes (i) light guides extending in a main scanning direction and configured to emit light from a light source toward a reading target moving relatively in a sub-scanning direction, the light from the light source being projected into end surfaces of the light guides in the main scanning direction, (ii) an optical filter arranged between the light source and the end surfaces of the light guides and configured to block or attenuate light having a specific wavelength from the light from the light source, (iii) a lens body to focus reflected light reflected by the reading target onto a light receiver to convert the reflected light into an electrical signal, and (iv) a lens holder. The lens holder includes a first positioner for positioning the light guides and a second positioner for positioning the optical filter.

A light guide including a light scattering portion that reflects light guided inside the light guide, and a light emitting surface portion emitting light reflected by the light scattering portion to outside the light guide. A light emitting surface portion includes first and second light emitting surface portions, the first light emitting surface portion has a longer circumferential length than that of the second light emitting surface portion in the transversal cross section, and circumference curvature of the first light emitting surface portion in the transversal cross section increases away from the second light emitting surface portion. A normal line to the light scattering portion, passing through the center of the light scattering portion in the transversal cross section, intersects with the first light emitting surface portion, at a point at a near side to the second light emitting surface portion in the transversal cross section.