| 摘要 |
PURPOSE:To correct the shading by the 4th power rule of cosine of a lens by increasing the photodetecting area of a photo-element much more as the spot is parted from the lens optical axis in a solid-state scanning image sensor. CONSTITUTION:When the center between a transmission original 2 being an object of reading and an image sensor 4 consisting of (2n+1)-set of photoelement groups arranged linearly is made coincident with the center of the optical system, the reflected light on the original reduced by the lens is projected on the image sensor by the quantity of light Kcos<4>theta at an incident angle theta with the optical axis. Thus, an area Si of the i-th photo-element 6 receiving the light reflected at an angle mui with the optical axis is selected as S0/cos<4>thetai, where S0 is the area of the photo-element 6 positioned on the optical axis, and the level deviation of a white signal is prevented by increasing the photodetecting area as the spot is parted from the optical axis similarly. |
