| 摘要 |
PROBLEM TO BE SOLVED: To provide an image reader capable of obtaining a read image high in quality by suppressing the vibration of the mirror of an exposure optical system caused by resonance with the driving source of a motor or the like. SOLUTION: In this image reader for reading the image of an original by moving the exposure optical system to/from an original platen where the original is placed, a weight 15 is attached to the mirrors 6 and 7 of the exposure optical system through an elastic body 14, and when the characteristic frequency of the mirrors 6 and 7 is defined as (ω), and the spring constant of the elastic body 14 is defined as (k) and the mass of the weight 15 is defined as (m), the spring constant (k) and the mass (m) are defined so as to satisfyω=√(k/m), so that the vibration is canceled by generating the vibration of reverse phase from the vibration of the mirrors 6 and 7. Also, a member is attached to the mirrors 6 and 7 so as to shift the characteristic frequency on a high-frequency side, so that the blurring at the time of reading the image is suppressed by reducing the amplitude of mirror vibration.
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