Image reader and imaging apparatus capable of reducing vibration and fluctuation in image reading

摘要

An image reader comprises a light source illuminating an original, an optical guide system configured to guide a light beam reflected from the original and conveying information about an image on the original, a light-receiving unit configured to receive the light beam guided by the optical guide system and to convert the information about the image into electric signals, a stay member holding the light-receiving unit, a balance weight configured to act on the stay member and to reduce oscillation of the light-receiving unit, and a balance-weight holding structure configured to hold the balance weight in an unrestrained state with respect to the stay member.