Abstract: A light guide having; an entrance portion; a light-splitting portion; a first and a second light guide portion; and a first and a second reflective portion provided in or on the first and second light guide portions, respectively. The first and second light guide portions emit light reflected by the first reflective portion and light reflected by the second reflective portion to outside as a first linear light beam and a second linear light beam, respectively. The light-splitting portion projects toward the entrance portion, and has a first inclined surface, a second inclined surface and a connecting section. The entrance portion has a light-diffusing section opposed to the connecting section in a direction of optical axis, and the light-diffusing section diffuses the light emitted from the point light source toward the first light guide portion and the second light guide portion.

Abstract: A light guide for use in an image reading apparatus. The light guide extends in a predetermined direction and includes: a reflecting surface being parallel to the predetermined direction; an emitting surface; and a prism configured to reflect light to the emitting surface. The prism includes a plurality of asperities formed on the reflecting surface. When viewed from a first direction orthogonal to the reflecting surface, at least one of the plurality of asperities includes a portion parallel to a predetermined curve or a predetermined straight line inclined from a second direction orthogonal to the predetermined direction.

Abstract: A light guide has a guide portion extending in a first direction. Light entering the guide portion through a first end is guided to a reading position. The guide portion has prisms provided on a bottom surface to be arranged in the first direction, and a turn-back member configured to turn light coming to a second end of the guide portion back toward the first end. Each of the prisms includes a first total-reflecting surface facing to the first end and a second total-reflecting surface facing to the second end. With respect to at least one of the prisms located within an area extending parallel to the first direction from the second end toward the first end by a predetermined distance, the angle of the first total-reflecting surface to the bottom surface is greater than the angle of the second total-reflecting surface to the bottom surface.

Abstract: A light guide has a guide portion extending in a first direction. Light entering the guide portion through a first end is guided to a reading position. The guide portion has prisms provided on a bottom surface to be arranged in the first direction, and a turn-back member configured to turn light coming to a second end of the guide portion back toward the first end. Each of the prisms includes a first total-reflecting surface facing to the first end and a second total-reflecting surface facing to the second end. With respect to at least one of the prisms located within an area extending parallel to the first direction from the second end toward the first end by a predetermined distance, the angle of the first total-reflecting surface to the bottom surface is greater than the angle of the second total-reflecting surface to the bottom surface.

Abstract: A light guide for use in an image reading apparatus. The light guide extends in a predetermined direction and includes: a reflecting surface being parallel to the predetermined direction; an emitting surface; and a prism configured to reflect light to the emitting surface. The prism includes a plurality of asperities formed on the reflecting surface. When viewed from a first direction orthogonal to the reflecting surface, at least one of the plurality of asperities includes a portion parallel to a predetermined curve or a predetermined straight line inclined from a second direction orthogonal to the predetermined direction.

Abstract: A light guide having; an entrance portion; a light-splitting portion; a first and a second light guide portion; and a first and a second reflective portion provided in or on the first and second light guide portions, respectively. The first and second light guide portions emit light reflected by the first reflective portion and light reflected by the second reflective portion to outside as a first linear light beam and a second linear light beam, respectively. The light-splitting portion projects toward the entrance portion, and has a first inclined surface, a second inclined surface and a connecting section. The entrance portion has a light-diffusing section opposed to the connecting section in a direction of optical axis, and the light-diffusing section diffuses the light emitted from the point light source toward the first light guide portion and the second light guide portion.