| 摘要 |
PROBLEM TO BE SOLVED: To provide a light guide, an illuminating device and an image reading apparatus that can make more efficient use of light.SOLUTION: The light guide has a first guide portion extending in a first direction and configured to guide light entering the guide portion to a reading position. The first guide portion includes: a plurality of first prisms provided on a first bottom surface extending in the first direction to be arranged in the first direction, and configured to total-reflect the light traveling in the first guide portion toward the reading position; and a turn-back member configured to turn light coming to a second end of the first guide portion back toward one side in the first direction, the second end located at the other side in the first direction. Each of the first prisms includes a first total-reflecting surface facing the one side in the first direction, and a second total-reflecting surface facing the other side in the first direction. With respect to one of the first prisms located within a first predetermined distance from the second end of the first guide portion toward the one side in the first direction, an angle of the first total-reflecting surface to the first bottom surface is larger than an angle of the second total-reflecting surface to the first bottom surface.SELECTED DRAWING: Figure 7 |
