| 摘要 |
PURPOSE:To make it possible to compensate fluctuation of the photoelectric conversion level, by providing a white part as a reference in a part of the read width of an image sensor and by controlling the level of the read signal on a basis of the read signal level of this white part. CONSTITUTION:The surface of the connection part of original holding plate 8 is coated with white paint so that white painted face 8a may be included in the part which is set wider than the width of original which read width X and Y of image sensor 7 tries to read. Therefore, the reference white signal (the signal for white painted face 8a of original holding plate 8) is included in the photoelectric conversion signal of any scanning line. Since the ratio of the reflection factor of white painted face 8a to the reflection factor of the original is fixed independently of fluctuation of brightness of the fluorescent lamp and fluctuation of the amplification degree of the signal amplifying circuit, the scanning signal level can be controlled by controlling the reference white signal level of the white painted face to a fixed value. |
